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CONTRIBUTIONS  TO  PALAEONTOLOGY 

FROM  THE  CARNEGIE  INSTITUTION  OF  WASHINGTON 


ADDITIONS  TO  THE  TERTIARY  HISTORY  OF  THE 
PELAGIC  MAMMALS  ON  THE  PACIFIC 
COAST  OF  NORTH  AMERICA 

BY 

REMINGTON  KELLOGG 


Published  by  the  Carnegie  Institution  of  Washington 

Washington,  April,  1925 


CARNEGIE  INSTITUTION  OF  WASHINGTON 

Publication  No.  348 


GopN  of  t  is  bm 

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APR  2  2  1925 


JUDD  &  DETWEILER,  INC. 
WASHINGTON,  D.C. 


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CONTENTS. 


I.  Two  Fossil  Physeteroid  Whales  from  California.  Plates  1  to  8,  Plate 
9  (figs.  1  and  2),  and  4  text-figs . 

II.  Fossil  Cetotheres  from  California.  10  text-figs. .  . . 

III.  A  New  Fossil  Sirenian  from  Santa  Barbara  County,  California.  Plates 

9  (fig.  3),  10  and  11 . 

IV.  New  Pinnipeds  from  the  Miocene  Diatomaceous  Earth  near  Lompoc, 

California.  Plates  12  and  13,  and  10  text-figs . ' . 

V.  Structure  of  the  Flipper  of  a  Pliocene  Pinniped  from  San  Diego  County, 

California.  29  text-figs . 

iii 


r4 

q) 

h 

r 


578413 


PAGE 

1-34 

35-56 

57-70 

71-96 

97-116 


I.  TWO  FOSSIL  PHYSETEROID  WHALES  FROM  CALIFORNIA. 


Hitherto,  the  only  occurrences  in  North  America  of  remains  of 
fossil  sperm  whales  have  been  confined  to  the  Atlantic  Coast.  In 
1920,  a  skull  of  an  apparently  unknown  physeteroid  was  found  in 
San  Luis  Obispo  County,  California,  and  afterwards  presented  by 
the  discoverer,  Mr.  Joseph  Walker,  to  the  Museum  of  Palaeontology 
of  the  University  of  California.  During  the  past  year,  portions  of 
the  rostrum  and  mandibles  of  a  much  larger  species,  which  were 
collected  by  Mr.  Charles  0.  Roe  in  1909  from  the  sea-cliff  near  the 
Santa  Barbara  lighthouse,  were  presented  to  the  United  States 
National  Museum.  The  infrequent  occurrence  of  sperm-whale  skulls 
lends  especial  interest  to  these  specimens  and  they  may  prove  to  be  of 
some  importance  in  the  general  problem  dealing  with  the  lines  of  evolu¬ 
tion  in  the  Cetacea  as  well  as  in  the  problem  of  geological  correlation. 

In  connection  with  studies  upon  fossil  toothed  whales,  notes  have 
been  made  from  time  to  time  upon  many  of  the  previously  described 
species,  and  some  of  these  observations  have  been  incorporated  in 
the  present  paper.  Inasmuch  as  these  descriptions  were  published 
in  different  years  and  in  several  different  countries,  it  seems  par¬ 
ticularly  desirable  to  give  a  brief  resume  of  what  is  actually  known 
concerning  those  fossil  cetaceans  which  appear  to  be  related  to  the 
California  specimens.  As  originally  defined,  most  of  the  fossil  forms 
would  be  excluded  from  the  family  Physeteridae,  for  these  species 
have  teeth  in  the  upper  jaws.  Acquisition  of  new  material  is  con¬ 
tinually  altering  our  concepts  of  the  lines  of  evolution  in  the  families 
and  genera  of  the  Cetacea,  as  illustrated  by  the  changes  in  the 
relations  of  the  various  bones  which  compose  their  skulls.  New 
structural  features,  or  possible  explanations  for  modifications  ob¬ 
served  in  living  genera,  are  frequently  supplied  by  each  discovery. 

Since  1846,  at  least  25  genera  have  been  proposed  for  remains  of 
fossil  cetaceans  which  at  one  time  or  another  have  been  referred  to 
as  physeteroids.  For  convenience  they  are  listed  alphabetically 
with  the  year  of  publication:  Balaenodon,  1846;  Diaphorocetus,  1894; 
Dinoziphius ,  1880;  Eucetus ,  1867;  Eudelphis ,  1872;  Graphiodon,  1870; 
Homoeocetus,  1867;  Hoplocetus,  1848-52;  Hypocetus,  1894;  Mesocetus, 
1892;  Ontocetus,  1869;  Orcopsis,  1876;  Orycterocetus,  1853;  Palaco- 
delphis,  1872;  Palaeodelphis,  1872;  Paracetus ,  1894;  Physeterula , 
1877;  Physetodon,  1879;  Physodon,  1872;  Platyrhynchus ,  1876; 
Priscophyseter ,  1886;  Prophyseter,  1905;  Scaldicetus,  1867;  Scaptodon, 
1918;  and  Thaiassocetus ,  1905.  Of  these  25  genera,  8  were  based  on 
the  5  known  skulls,  1  on  the  extremity  of  a  rostrum,  1  on  an  imperfect 
mandible,  2  on  vertebrae,  and  the  remainder  on  1  or  more  teeth. 

l 


2  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast . 

Furthermore,  some  42  specific  names  have  been  applied  to  remains 
of  these  cetaceans  found  in  various  parts  of  the  world.  To  attempt  an 
orderly  classification  of  this  large  number  of  very  imperfectly  known 
forms  is  well-nigh  impossible  without  having  access  to  the  original 
material,  and  in  event  of  that  possibility  it  is  extremely  doubtful  if 
anything  of  importance  would  be  added  to  our  present  knowledge. 
Many  of  these  species  are  known  to  the  writer  only  from  the  original 
descriptions,  and  some  of  these  specimens  have  never  been  figured. 
Those  species  which  have  been  described  from  teeth  will  be  difficult 
to  allocate  until  skulls  are  found.  It  is  very  likely  that  additional 
material  will  show  that  some  of  them  belong  to  other  families,  for 
large  tusk-like  teeth  are  present  in  one  or  more  members  of  three 
families  of  living  cetaceans. 

Abel 1  has  attempted  to  reduce  the  number  of  generic  types  by 
making  the  following  allocations,  although  it  appears  to  the  writer 
that  they  are  not  justified  in  all  cases.  The  genera  Balaenodon , 
Dinoziphius,  Eucetus ,  Eudelphis,  Homoeocetus,  Hoplocetus ,  Palaco- 
delphis,  Palaeodelphis ,  and  Physodon  were  referred  to  the  genus 
Scaldicetus;  Orcopsis  and  Platyrhynchus  were  allocated  to  the  genus 
Physeterula.  One  skull  from  Patagonia  has  had  four  generic  names, 
Hypocetus,  Mesocetus,  Paracetus,  and  Diaphorocetus,  applied  to  it 
and  of  these  the  last  mentioned  has  priority.  It  is  possible  that  some 
of  the  eight  generic  names  which  are  thus  left,  Graphiodon,  Ontocetus, 
Orycterocetus,  Physetodon,  Priscophyseter ,  Prophyseter ,  Scaptodon,  and 
Thalassocetus,  may  become  synonyms  when  more  adequate  material 
is  obtained. 

From  a  geological  standpoint,  the  history  of  the  Physeteridae  or 
sperm  whales  is  comparatively  short,  for  the  oldest  types  now  known 
were  obtained  in  the  Patagonian  tuff  formation  on  the  coast  of  Chubut 
Territory,  Argentine  Republic.  Two  skulls,  representing  different 
genera,  have  been  obtained  from  this  Lower  Miocene  formation.  In 
dimensions  and  general  form,  the  largest  of  these  skulls  is  very  closely 
allied  to  a  fossil  sperm  whale  from  the  St.  Marys  formation  of  Mary¬ 
land,  and  seems  distinguishable  from  the  smaller  form,  Diaphorocetus 
poucheti,  by  differences  in  the  conformation  of  the  maxilla  along  the 
lateral  wall  of  the  supracranial  basin,  in  the  number  and  position  of 
the  maxillary  foramina,  and  possibly  by  the  number  of  teeth  in  the 
upper  jaw.  The  characteristic  features  of  the  living  sperm  whales, 
as  for  instance  the  development  of  the  great  supracranial  basin,  were 
well  developed  in  these  early  Miocene  forms,  and  the  largest  form 
attained  a  considerable  size  for  the  type  skull  is  nearly  6  feet  long. 

The  type  skull  of  Diaphorocetus  poucheti  is  in  a  fair  state  of  pres¬ 
ervation.  The  supraoccipital  is  damaged  on  each  side,  portions  of 

1 0.  Abel,  Les  Odontocetes  du  Bolderien  (Miocene  superieur)  d’ Anvers,  Mem.  Mus.  roy. 
d’hist.  nat.  de  Belgique,  Bruxelles,  vol.  3,  pp.  52,  75,  1905. 


Two  Fossil  Physeteroid  Whales. 


3 


the  right  and  left  maxillae  and  premaxillae  are  missing  at  the  level  of 
the  nasal  passages;  the  left  lachrymal  and  jugal  are  lost,  as  well  as  a 
portion  of  the  left  supraorbital  process  of  the  frontal.  The  distal 
end  of  the  rostrum  has  been  broken  off  and  the  ends  of  the  maxillae 
have  spread  apart.  No  teeth  are  in  place,  but  the  alveoli  on  the 
distal  half  of  the  rostrum  are  relatively  large  and  well  defined.  This 
skull  was  found  at  “  Bahia  Nueva — immediaciones  de  Puerto 
Madryn,  Territorio  del  Chubut,  Lat.  42°  30'  Sud,”  Patagonia,  Argen¬ 
tine  Republic,  in  the  Patagonian  tuff  formation.  The  type  is  now 
preserved  in  the  Museo  de  La  Plata. 

The  genus  Mesocetus ,  which  Moreno1  proposed  for  this  species 
was  preoccupied,  having  been  given  to  a  genus  of  fossil  whalebone 
whales  by  Van  Beneden2  in  1883.  It  was,  therefore,  renamed 
Diaphorocetus  by  Ameghino3  in  1894,  and  assigned  to  the  family 
Pontoplanodidae.  Lydekker,4  not  knowing  that  Ameghino  had 
renamed  the  genus,  gave  this  species  the  name  of  Hypocetus.  He 
refigures  the  type  skull  and  assigns  the  genus  to  the  family  Physo- 
dontidae.  Cope5  shows  that  Lydekker  in  the  text  proposes  to  call 
the  genus  Paraceius  but,  in  the  heading  and  on  the  plate,  the  latter 
cites  the  form  as  Hypocetus.  It  appears  that  Lydekker  changed 
Paracetus  to  Hypocetus  after  writing  the  account  of  this  form,  and 
neglected  to  make  the  correction  in  the  text.  This  interpretation 
is  borne  out  by  the  following  quotation  from  an  advance  notice 
by  that  writer:6  “ Another  member  of  the  same  family  (i.  e.  Physo- 
dontidae)  is  represented  in  the  Museum  by  a  smaller  cranium,  to 
which  I  have  assigned  the  name  Hypocetus Cope  refers  Moreno’s 
species  to  the  family  Physeteridae.  Ameghino7  cites  some  of  the 
preceding  allocations  and  expresses  the  opinion  that  this  species 
should  be  placed  in  the  Physeteridae,  thus  agreeing  with  Cope  that 
Diaphorocetus  does  not  belong  to  some  other  family.  Little  or  noth¬ 
ing  further  was  published  in  regard  to  this  genus  until  1905  when 
Professor  Abel8  commented  on  it  as  follows: 

I  would  remark  that  the  relationship  between  the  genera  Scaldicetus  [  =  Physodon, 
in  part]  and  Hxjpocetus  [  =  Diaphorocetus]  are  uncertain,  as  the  teeth  in  this  latter  form, 
found  in  the  Miocene  of  Chubut,  Patagonia,  are  unknown.  The  skull  is  different  from 
that  of  Scaldicetus,  but  belongs  without  doubt  to  a  physeterid. 

1  F.  P.  Moreno,  Noticias  sobre  algunos  cetaceos  fdsiles  y  actuales  de  la  Republica  Argentina 
conservados  en  el  Museo  de  La  Plata,  Revista  del  Museo  de  La  Plata,  vol.  3,  p.  395,  pi.  10,  1892. 

2  P.  J.  Van  Beneden,  Les  Mysticetes  h  courts  fanons  des  sables  des  environs  d’Anvers,  Bull. 
Acad.  Roy.  Sci.  de  Belgique,  Bruxelles,  ser.  2,  vol.  50,  pp.  22-23,  1880. 

3  F.  Ameghino,  Enumeration  synoptique  des  especes  de  mammiferes  fossiles  des  formations 
Eocenes  de  Patagonie,  Bol.  Acad.  Nac.  Ciencias  de  Cordoba,  Buenos  Aires,  vol.  13,  p.  437, 
February,  1894. 

4  R.  Lydekker,  Contributions  to  a  knowledge  of  the  fossil  vertebrates  of  Argentina:  II.  Cetacean 

skulls  from  Patagonia,  Annales  del  Museo  de  La  Plata,  vol.  2,  for  1893,  p.  8.  April,  1894. 

6  E.  D.  Cope,  Fourth  contribution  to  the  marine  fauna  of  the  Miocene  period  of  the  United 
States,  Proc.  Amer.  Philos.  Soc.,  Philadelphia,  vol.  34,  pp.  135-136,  1895. 

*  R.  Lydekker,  The  La  Plata  museum,  Nat.  Sci.,  vol.  4,  No.  24,  p.  125,  February,  1894. 

7  F.  Ameghino,  Notas  sobre  cuestiones  de  geologia  y  paleontologia  Argentinas,  Bol.  Inst. 
Geografico  Argentino,  vol.  17,  pp.  87-119  (separate,  footnote,  p.  15),  1896. 

8  O.  Abel,  Les  Odontocetes  du  Bolderien  (Miocene  superieur)  d’Anvers,  Mem,  Mus.  roy, 
d’hist.  nat.  de  Belgique,  Bruxelles,  vol.  3,  p.  70,  1905. 


4 


Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


It  will  be  noted  that  there  seems  to  be  no  division  of  opinion  re¬ 
garding  the  general  relationships  of  Diaphorocetus.  The  large  supra- 
cranial  basin,  the  unsymmetrical  nasal  passages,  the  broad  depressed 
basal  portion  of  the  rostrum,  the  expanded  post-narial  process  of  the 
right  premaxilla,  the  narrow  and  deep  antorbital  notches  all  indicate 
its  relation  to  the  Physeteridae.  The  most  salient  characters  by 
which  it  is  distinguished  from  the  recent  genus  Physeter  are  the 
presence  of  well-defined  alveoli  in  the  maxillae,  of  which,  when  the 
skull  was  intact,  there  were  more  than  13  on  each  side,  and  by  the 
mesial  constriction  of  the  rostrum.  Some  rudimentary  teeth  are 
occasionally  found  in  Physeter ,  but  the  alveolar  septa  are  lacking, 
the  groove  being  continuous  in  young  skulls  and  more  or  less  rudi¬ 
mentary. 

Comparison  of  Diaphorocetus  with  other  extinct  physeteroids  from 
later  formations  is  rendered  difficult  on  account  of  the  fragmentary 
condition  of  the  skulls  of  the  latter  thus  far  described.  The  European 
Upper  Miocene  genus  Physeterula 1  is  known  only  from  one  or  two 
imperfect  crania  lacking  the  rostrum  and  a  mandible  with  teeth. 
The  mandibular  teeth  are  worn  on  the  superior  and  posterior  surfaces, 
from  which  it  is  inferred  that  teeth  were  present  in  the  upper  jaw 
also,  but  as  the  rostrum  is  lacking  its  form  can  not  be  determined. 
It  is  probable,  however,  that  the  genus  is  quite  closely  related  to 
Diaphorocetus  though  the  type  species,  Physeterula  dubusii,  is  much 
larger  than  that  form.  It  appears  that  the  teeth  of  Physeterula  have 
lost  their  enamel.  With  the  exception  of  Miller1 2  who  is  inclined  to 
refer  Physeterula  dubusii  Van  Beneden  and  Physodon  patagonicus 
Lydekker,  as  he  says  “  without  too  great  hesitation,”  to  the  Delphi- 
ninae,  the  consensus  of  opinion  as  expressed  in  the  published  state¬ 
ments  of  various  writers,  including  those  who  actually  have  had  the 
opportunity  to  study  the  specimens,  seems  to  be  in  favor  of  asso¬ 
ciating  these  forms  with  the  sperm  whales. 

Any  attempt  to  elucidate  the  status  of  the  large  toothed  cetacean 
from  Chubut  Territory,  Patagonia,  described  by  Lydekker3  as 
Physodon  patagonicus  will  be  somewhat  involved,  for  the  original 
description  is  so  brief  that  many  important  details  are  necessarily 
omitted  and  the  generic  name  is  preoccupied.  As  originally  applied, 
Physodon  leccense  was  given  by  Gervais4  to  teeth  from  the  Miocene 
sand  stone  of  Lecce  in  the  compartment  of  Puglia,  Italy,  which 
Costa5 6  had  referred  to  the  genus  Phoca.  This  limestone  has  been 

1  O.  Abel,  op.  cit.,  vol.  3,  pp.  74-82,  1905. 

2  G.  S.  Miller  jr.,  The  telescoping  of  the  cetacean  skull,  Smithsonian  Misc.  Coll.,  vol.  76,  No. 
5,  Publ.  2720,  pp.  44-45,  49,  August  31,  1923. 

3  R.  Lydekker,  Contributions  to  a  knowledge  of  the  fossil  vertebrates  of  Argentina:  II.  Cetacean 
skulls  from  Patagonia,  Annales  del  Museo  de  La  Plata,  vol,  2  for  1893,  pp.  4-7,  pi.  2,  April  1894. 

4  P.  Gervais,  Coup  d’Oeil  sur  les  Mammiferes  fossiles  de  l’ltalie,  Bull.  Soc.  Geol.  de  France, 

Paris,  ser.  3,  vol.  29,  p.  101,  1872. 

6  O.  G.  Costa,  Paleontologia  del  Regno  di  Napoli,  Atti  della  Accad.  Pontaniana,  Naples,  vol. 
5,  fasc.  5,  pp.  242-244,  pi.  1,  figs.  1-2,  1853. 


Two  Fossil  Physeteroid  Whales. 


5 


assigned  to  the  Langhian  stage  of  the  Lower  Miocene.  Some  of 
these  teeth  have  been  figured1  and  discussed,  but  it  is  not  necessary 
to  make  any  further  mention  of  this  Italian  form,  because  Physodon 
of  Haldemann2  has  many  years  priority.  This  necessitates  the 
selection  of  another  generic  name  for  the  Patagonian  species.  A 
survey  of  the  literature  shows  that  Abel3  has  attempted  to  meet  this 
difficulty  by  referring  Physodon  patagonicus  to  the  genus  Scaldicetus, 
but  as  will  be  shown  later  this  association  may  not  be  entirely 
justified. 

Winge4  has  revived  the  genus  Hoplocetus  of  Gervais  for  those  fossil 
physeteroids  which  have  teeth  coated  with  enamel  in  the  upper  jaws. 
Hoplocetus  crassidens,5  the  type  species,6  was  based  upon  two 
teeth,  111  mm.  and  121  mm.  long  respectively,  obtained  from  the 
“falun”  of  Romans  in  the  department  of  Drome,  France.  These 
enamel-crowned  teeth  are  slightly  curved  and  are  characterized 
by  the  excessive  thickness  of  the  cement  as  well  as  by  the  well- 
marked  constriction  of  the  base  of  the  crown.  This  constriction 
undoubtedly  is  indicative  of  old  age.  Deperet7  states  that  the  teeth 
of  Physodon  differ  from  those  of  Hoplocetus  in  that  the  enamel  of  the 
crown  passes  into  the  cement  part,  or  root,  without  forming  an 
enlargement  at  the  base,  as  in  the  latter  genus.  This  also  may  be  a 
peculiarity  associated  with  growth,  but  the  important  fact  to  be 
noted  is  that  isolated  teeth  do  not  afford  at  present  any  means  for 
determining  the  type  of  skull  to  which  they  may  belong.  At  least 
five  types  of  fossil  physeteroid  skulls  which  possess  teeth  in  the 
upper  jaw  are  now  known  from  Miocene  formations,  and  there  is  no 
assurance  that  those  of  the  Helvetian  Hoplocetus  actually  pertain 
to  any  one  of  these  cetaceans.  There  appears  to  be  more  justifica¬ 
tion  for  allocating  imperfectly  known  forms  from  the  same  formation, 
or  from  formations  of  similar  age,  to  some  better  preserved  specimen, 
than  there  is  for  lumping  one  or  more  forms  based  on  similarly 
inadequate  material  and  from  deposits  which  are  not  conceded  to  be 
equivalent  in  time  with  some  one  well-known  type.  In  view  of  the 
present  uncertainty  which  surrounds  the  availability  of  previously 

1  P.  J.  Van  Beneden  and  P.  Gervais,  Ost6ographie  des  C6tac6s  vivants  et  fossiles,  Paris,  pp. 
334-335,  pi.  20,  figs.  16-18,  1880. 

2  S.  S.  Haldemann,  A  monograph  of  the  Limniades  and  other  freshwater  univalve  shells  of 
North  America,  Supplement  to  Part  I,  p.  2,  October  1840. 

3  O.  Abel,  Les  Odontocetes  du  Bolderien  (Miocene  sup6rieur)  d’ Anvers,  Mem.  Mus.  roy. 
d’hist.  nat.  de  Belgique,  Bruxelles,  vol.  3,  p.  52,  1905. 

4  H.  Winge,  A  review  of  the  interrelationships  of  the  Cetacea,  Smithsonian  Misc.  Coll.,  vol. 

72,  No.  8,  Publ.  2650,  pp.  42,  44,  92,  1921. 

6  P.  Gervais,  Zoologie  et  PalSontologie  Frangaises  (Animaux  Vert6bres)  ou  Nouvelles  Re- 
cherches  sur  les  Animaux  Vivants  et  Fossiles  de  la  France,  vol.  1,  Cahier  21,  p.  161,  vol.  2,  explan, 
for  pi.  20,  figs.  10-11  (page  not  numbered),  1848-52. 

6  O.  P.  Hay,  Bibliography  and  catalogue  of  the  fossil  vertebrata  of  North  America,  Bull.  No. 
179,  U.  S.  Geol.  Surv.,  Dept.  Interior,  p.  596.  1902  (type  fixed). 

7  C.  Deperet,  Recherches  sur  la  succession  des  faunes  de  vertebres  Miocenes  de  la  val!6e  du 
Rhdne,  Archiv.  Mus.  d’hist.  nat.  de  Lyon,  vol.  4,  p.  276,  1887. 


6  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast . 

proposed  genera,  it  seems  desirable  to  designate  Physodon  patagonicus 
Lydekker  as  the  type  of  a  new  genus,  which  may  be  called  Idiorophus. 

This  genus  is  based  on  a  skull  with  most  of  the  brain  case  missing, 
in  which,  however,  nearly  all  the  teeth  are  present,  both  mandibles, 
and  “a  certain  number  of  dorsal  and  caudal  vertebrae.”  When 
complete  the  skull  was  about  6  feet  long.  The  species  patagonicus  is 
characterized  by  the  number  and  position  of  the  maxillary  foramina, 
the  long  laterally  compressed  extremity  of  the  rostrum  with  arched 
premaxillae,  and  teeth  in  both  jaws.  The  teeth  are  large,  long,  terete, 
and  but  little  curved,  the  crowns  being  conical  and  covered  with 
rugose  enamel.  On  each  side,  3  of  the  upper  teeth  at  the  end  of  the 
rostrum  are  situated  in  the  premaxilla.  While  the  supracranial 
basin  of  the  skull,  characteristic  of  the  physeteroid  whales,  is  strongly- 
developed  in  this  species,  the  genus  Idiorophus  is  distinguishable  from 
Physeter  by  the  curvature  of  the  lateral  margins  of  the  rostrum,  the 
shape  of  the  supraorbital  process  of  the  frontal,  and  the  presence  of 
numerous  maxillary  teeth.  From  Diaphorocetus  it  differs,  apparently, 
by  the  greater  number  of  maxillary  foramina,  by  the  elevation  of  the 
premaxillae  on  the  rostrum,  and  the  fact  that  the  premaxillae  are  in 
contact  along  their  inner  margins  and  thus  completely  roof  the 
vomerine  gutter.  The  figures  of  Diaphorocetus  poucheti  and  those  of 
Physodon  patagonicus  given  by  Lydekker  are  from  different  points  of 
view,  but  those  for  the  latter  give  one  the  impression  that  in  addition 
to  other  features  they  illustrate  a  more  massive  form.  It  would  not, 
however,  be  necessary  on  that  account  alone  to  consider  it  as  generi- 
cally  distinct. 

The  teeth  of  Idiorophus  patagonicus  (Lydekker)  present  the 
characters  of  a  young  Scaldicetus  and  closely  resemble  teeth  of  young 
individuals  of  Scaldicetus  grandis  from  the  Anversian  stage  of 
Antwerp,  Belgium,  described  by  Du  Bus1  under  the  names  of 
Palaeodelphis  coronatus  and  Palaeodelphis  minutus.  They  are, 
however,  intermediate  in  size  between  these  two,  and  apparently  do 
not  show  the  characteristic  development  of  an  anterior  and  a  pos¬ 
terior  cutting  edge  as  in  the  latter.  The  teeth  of  the  Patagonian 
cetacean  have  relatively  longer  crowns. 

Considering  the  evidence  as  a  whole,  it  seems  reasonable  to  suppose 
that  Physodon  patagonicus  Lydekker  really  belongs  to  some  genus 
other  than  Scaldicetus ,  but  whether  they  exhibit  any  close  relationship 
can  scarcely  be  decided  until  additional  material  representing  both 
genera  shall  have  been  obtained,  or  at  least  until  the  type  skull  of 
the  former  is  re-examined. 

1  B.  A.  L.  Du  Bus,  Mammiferes  nouveaux  du  Crag  d’Anvers,  Bull.  Acad.  Roy.  des  Sci.,  des 
Lettres  et  des  Beaux-Arts  de  Belgique,  Bruxelles,  ser.  2,  vol.  34,  No.  12,  pp.  504,  505,  1872. 

O.  Abel,  Les  Odontocetes  du  Bolderien  (Miocene  Sup6rieur)  d’  Anvers,  Mena.  Mus.  roy.  d’hist. 
nat.  de  Belgique,  Bruxelles,  vol.  3,  p.  64,  fig.  3,  and  p.  65,  fig.  4,  1905. 


Two  Fossil  Physeteroid  Whales. 


7 


The  only  European  species  of  Scaldicetus  which  can  be  compared 
with  Idiorophus  patagonicus  (Lydekker)  is  Scaldicetus  mortezelensis 
from  the  Anversian  stage  of  the  Antwerp  basin,  Belgium.  A  very 
imperfect  skull  of  this  species  has  been  figured  by  Abel,1  from  which 
it  would  appear  that  the  rostrum  is  narrower  at  the  base,  but  the 
interspace  between  the  premaxillae  at  the  base  of  the  rostrum  is 
wide  as  in  Diaphorocetus  poucheti. 

Forty-five  teeth,  measuring  from  200  to  240  mm.  in  length  and 
assumed  to  belong  to  one  individual,  formed  the  basis  for  the  species 
caretti ,2  the  type  of  the  genus  Scaldicetus.  These  teeth  are  slightly 
curved  and  the  enamel  on  the  crown  is  striated  longitudinally.  For 
this  reason,  teeth  are  the  sole  criterion  for  the  genus  Scaldicetus  and, 
on  basis  of  similarity  observed  between  the  teeth,  Abel3  referred 
Eudelphis  mortezelensis  Du  Bus4  to  this  genus.  Two  teeth  are 
known  for  this  species,  and  one  of  these  measures  88  mm.  in  length, 
of  which  11  mm.  is  occupied  by  the  crown.  All  comparisons  with 
Scaldicetus,  as  mentioned  in  the  foregoing  paragraph,  must  be  made 
upon  this  skull. 

Teeth  found  in  the  United  States  and  Europe  resembling  those  of 
Scaldicetus  caretti  and  originally  described  under  different  generic 
and  specific  names,  have  been  assembled  by  Professor  Abel5 6  under 
the  names  of  Scaldicetus  caretti,  grandis,  and  mortselensis.  According 
to  his  carefully  considered  diagnosis  of  the  genus  Scaldicetus,  the 
teeth  in  young  animals  are  elongated,  and  nearly  terete,  wdth  rather 
short  crowns,  which  are  coated  with  longitudinally  striated  enamel 
and  present  an  anterior  and  posterior  cutting  edge  or  carina  as  in 
Squalodon.  The  enamel  crown  does  not  terminate  obliquely  where 
it  joins  the  root,  as  in  Squalodon,  but  the  line  of  junction  is  usually 
transverse.  In  older  individuals,  the  top  of  the  root  becomes  worn 
away  anteriorly  and  posteriorly,  producing  a  constriction  between  it 
and  the  crown,  while  the  apex  of  the  latter  suffers  a  transverse 
truncation.  In  still  older  individuals,  the  constriction  between  the 
crown  and  root  becomes  deeper,  and  the  crown  finally  breaks  off, 
leaving  only  the  root  in  the  jaw.  This  root  becomes  gibbous  near 
the  middle,  owing  to  the  increase  in  thickness  of  the  cement  layer, 
while  the  core  of  dentine  is  exposed  at  the  top.  The  surface  of  the 
dentine,  like  the  enamel,  is  marked  by  longitudinal  grooves. 

Besides  the  teeth  of  Scaldicetus  grandis  from  the  Upper  Miocene  of 
Antwerp,  mentioned  above,  numerous  other  teeth  described  under 
various  generic  and  specific  names  have  been  allocated  to  that  species 

1  O.  Abel,  op.  cit.,  vol.  3,  p.  67,  fig.  5,  1905. 

2  B.  A.  L.  Du  Bus,  Sur  quelques  Mammiferes  du  Crag  d’Anvers,  Bull.  Acad.  Roy.  des  Sci.,  des 
Lettres,  et  des  Beaux-Arts  de  Belgique,  Bruxelles,  ser.  2,  vol.  24,  No.  12,  pp.  567-568,  1867. 

3  O.  Abel,  op.  cit.,  vol.  3,  p.  67,  1905. 

4  B.  A.  L.  Du  Bus,  Mammiferes  nouveaux  du  Crag  d’Anvers,  Bull.  Acad.  Roy.  des  Sci.,  des 

Lettres,  et  des  Beaux-Arts  de  Belgique,  Bruxelles,  ser.  2,  vol.  34,  No.  12,  p.  500,  1872. 

6  O.  Abel,  op.  cit.,  vol.  3,  pp.  56-68,  1905. 


8  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 

by  Professor  Abel.  They  are  from  Belgium,  Holland,  England, 
Northern  Germany,  and  France.  Some  belong  to  the  Middle  and 
Upper  Miocene  of  Continental  Europe,  and  others  to  the  Red  Crag 
of  Suffolk,  England,  which  is  a  Pliocene  formation. 

Another  group  of  species  described  under  different  names,  but 
assigned  to  Scaldicetus  caretti  Du  Bus  by  Abel  are  also  from  the 
Miocene  and  Pliocene  of  Europe,  including  localities  in  Denmark, 
Holland,  Belgium,  Germany,  England,  France,  Italy,  and  Malta; 
and  likewise  from  the  United  States.  One  of  the  North  American 
species  assigned  to  Scaldicetus  caretti  was  originally  described  by 
Leidy* 1  in  1877  under  the  name  of  Dinoziphius  carolinensis.  This 
species  was  based  on  a  single  tooth  belonging  to  an  old  individual  and 
now  in  the  Academy  of  Natural  Sciences  of  Philadelphia,  which  was 
obtained  by  the  Pacific  Guano  Company  in  the  course  of  their  opera¬ 
tions  in  the  Ashley  River  phosphate  deposits  near  Charleston,  South 
Carolina.  The  crown  with  its  enamel  is  missing;  the  cement  layer 
of  the  root  is  rather  thick  (9  mm.),  giving  it  a  quite  gibbous  form, 
and  the  dentine  does  not  show  transverse  wavy  lines.  As  preserved, 
this  tooth  measures  211  mm.  in  length,  with  a  maximum  transverse 
diameter  of  80  mm.,  while  the  greatest  diameter  of  the  end  of  the 
root  is  about  23  mm. 

The  other  North  American  species  allocated  with  Scaldicetus 
caretti  by  Abel  has  been  uniformly'  known  in  American  literature 
since  1868  under  the  name  originally  given  it  by  Leidy,2  Hoplocetus 
obesus.  The  species  obesus  was  originally  founded  on  2  teeth  from 
the  “  post-pliocene  formation  of  Ashley  River,  in  the  vicinity  of 
Charleston,”  South  Carolina,  obtained  by  Professor  F.  S.  Holmes. 
The  largest  tooth  is  imperfect,  with  part  of  the  enamel  crown  worn 
away  and  the  end  of  the  root  missing.  The  band  of  enamel  on  the 
crown  is  striated  longitudinally  and  measures  about  6  mm.  in  depth. 
The  root  is  fusiform,  slightly  curved,  with  an  axis  of  dentine  about 
equal  in  diameter  to  the  crown,  and  a  thick  layer  of  cement.  In  a 
straight  line  the  largest  tooth  measures  93  mm.  and  the  greatest 
diameter  of  the  root  is  approximately  40  mm.  The  teeth  of  young 
individuals  of  Scaldicetus  caretti  when  complete  have  the  crowns 
covered  with  rugose  enamel,  but  with  increasing  age  and  wear  the 
roots  become  thickly  coated  with  cement  and  the  crowns  assume 
many  different  forms  and  are  finally  worn  away  altogether,  leaving 
only  the  thick  fusiform  root.  A  lack  of  understanding  of  these 
changes  has  caused  the  establishment  of  a  large  number  of  nominal 
genera  and  species. 

1  J.  Leidy,  Description  of  vertebrate  remains,  chiefly  from  the  phosphate  beds  of  South  Caro¬ 
lina,  Journ.  Acad.  Nat.  Sci.  Philadephia,  ser.  2,  vol.  8,  p.  216,  pi.  34,  fig.  6,  1877. 

1  J.  Leidy,  Notice  of  some  extinct  cetaceans,  Proc.  Acad.  Nat.  Sci.  Philadelphia,  vol.  20,  pp. 

196-197,  August  1868. 


Two  Fossil  Physeteroid  Whales. 


9 


The  type  tooth  of  Dinoziphius  carolinensis  is  too  large  and  those 
of  Hoplocetus  obesus  are  too  small  to  bear  any  close  relation  to  the 
large  physeteroid  from  the  Upper  Miocene  St.  Marys  formation  of 
Maryland  described  by  Cope1  as  Paracetus  mediatlanticus.  The 
type  specimen  consists  in  an  incomplete  skull  (plates  4,  5) ;  the  right 
supraorbital  process  of  the  frontal  is  present  though  much  worn  and 
incomplete,  but  the  braincase  and  the  extremity  of  the  rostrum  are 
missing.  The  rostrum  of  the  type  specimen  was  formerly  included 
in  the  exhibit  of  the  Maryland  Geological  Survey  in  the  Statehouse 
at  Annapolis.  A  large  fragment  consisting  of  the  lateral  crest  of  the 
maxilla  and  the  supraorbital  process  of  the  frontal  remained  in  the 
collection  of  Johns  Hopkins  University.  Both  of  these  specimens 
have  been  placed  on  deposit  in  the  United  States  National  Museum 
where  they  have  been  fitted  together.  The  skull  was  found  at  Drum 
Point  on  the  western  shore  of  Chesapeake  Bay,  Calvert  County, 
Maryland. 

This  species  has  arched  premaxillae  and  a  broad,  sloping,  basal  area 
as  in  the  South  American  Lower  Miocene  Idiorophus  patagonicus. 
The  maxillae  and  premaxillae  were  also  probably  prolonged  ante¬ 
riorly,  forming  a  beak  as  in  that  species.  The  skull  appears  to  differ 
from  that  of  I.  patagonicus  in  the  wide  interval  between  the  opposite 
margins  of  the  premaxillae,  thus  exposing  the  mesorostral  gutter,  the 
greater  depth  of  the  lateral  crest  of  the  maxilla  at  the  level  of  the 
orbit,  as  well  as  in  the  position  of  the  maxillary  foramina.  Eight 
alveoli  are  present  in  each  maxilla,  but  they  are  not  deep,  not  more 
than  50  mm.  at  the  most;  the  greatest  transverse  diameter  of  the  last 
alveolus  at  the  surface  is  about  21  mm.,  that  for  the  fourth  is  27  mm., 
while  that  for  the  anterior  is  23.5  mm. 

As  will  become  apparent  from  an  examination  of  Moreno’s  figures 
and  a  careful  study  of  the  descriptions  given  by  that  writer  and 
by  Lydekker,  Paracetus  mediatlanticus  of  Cope  does  not  bear  any 
generic  relationship  to  Diaphorocetus  poucheti.  If  they  represented 
different  species  of  the  same  genus,  for  Paracetus  is  a  synonym  of 
Diaphorocetus ,  one  would  expect  to  find  certain  minor  differences,  but 
rarely  if  ever  do  such  differences  involve  the  position  and  number  of 
important  foramina  for  nerves  and  blood-vessels.  In  Diaphorocetus 
poucheti  the  largest  maxillary  foramen  connecting  with  the  infra¬ 
orbital  system  is  situated  posterior  to  the  antorbital  notch,  while  in 
mediatlanticus  it  is  situated  at  the  level  of  it.  The  great  depth  and 
unusual  thickening  of  the  maxilla  on  the  lateral  wall  of  the  supra- . 
cranial  basin  at  the  level  of  the  orbit  as  well  as  other  peculiarities 
defined  in  the  key  which  follows  this  discussion  distinguish  the 
species  mediatlanticus  from  Diaphorocetus  poucheti.  Such  a  grouping 

1  E.  D.  Cope,  Fourth  contribution  to  the  marine  fauna  of  the  Miocene  period  of  the  United 
States,  Proc.  Amer.  Philos.  Soc.,  Philadelphia,  vol.  34,  No.  147,  pp.  135-137,  189* 


10  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


of  skulls  exhibiting  different  types  of  supracranial  modifications  would 
be  wholly  at  variance  with  accepted  methods  of  classification.  In 
view  of  these  differences,  it  is  necessary  to  apply  some  generic  name 
other  than  Diaphorocetus  to  the  large  physeteroid  from  the  St.  Marys 
formation. 

Fortunately,  an  Upper  Miocene  genus  does  appear  to  be  available 
for  this  species.  This  genus1  was  originally  based  on  two  rather  large 
teeth  of  peculiar  form  and  appearance,  “  fragments  of  both  sides  of 
the  lower  jaw,  and  a  portion  of  a  rib.”  These  specimens  should  be 
in  the  Academy  of  Natural  Sciences  of  Philadelphia,  but  so  far  as  I 
am  aware  they  have  not  been  seen  by  anyone  since  1869  when  Leidy 
again  mentioned  and  described  them.  At  that  time,  Leidy  men¬ 
tioned  and  described  a  fragment  of  an  upper  jaw  “accompanying 
the  teeth,”  but  said  nothing  of  fragments  of  the  lower  jaw  nor  of  a 
rib.  The  original  description  was  probably  faulty  in  this  respect. 
These  specimens  are  from  an  Upper  Miocene  formation  in  Virginia 
and  were  obtained  by  Leidy  from  Professor  Francis  B.  Holmes  of 
Charleston,  South  Carolina.  Leidy’s  clear  description  and  excellent 
figures  of  the  type  teeth  of  Orycterocetus  quadratidens ,2  published  in 
1869,  leave  no  doubt  as  to  their  character,  but  the  question  of  their 
relationship  to  the  other  species  mentioned  above,  particularly  to 
Cope’s  Paracetus  mediatlanticus ,  is  of  special  interest. 

The  description  of  the  portion  of  the  rostrum  which  accompanied 
the  type  teeth,  and  which  Leidy  in  1869  called  a  portion  of  the  upper 
jaw,  is  as  follows: 

A  fragment  of  the  upper  jaw  accompanying  the  teeth,  about  eight  inches  long,  ac¬ 
commodated  as  many  teeth.  The  alveoli  were  separated  by  thin  partitions,  and  their 
bottom  was  separated  from  the  dental  canal  by  a  thick  layer  of  porous  bone.  Two 
alveoli,  perfect  at  their  outer  parapet,  are  an  inch  and  three-fourths  deep  by  an  inch 
in  diameter.  The  outer  part  of  the  jaw  at  the  side  of  these  alveoli  is  three  and  a  quar¬ 
ter  inches  deep. 

If  we  consider  that  this  fragment  really  belonged  with  the  type 
teeth  and  that  the  latter  originally  had  their  place  in  it,  we  can  picture 
Orycterocetus  quadratidens  as  a  species  of  approximately  the  same 
size  as  Paracetus  mediatlanticus ,  with  a  row  of  slender  upper  teeth 
extending  about  3  inches  beyond  the  maxilla  and  a  similar  row  in 
the  mandible.  A  peculiarity  of  the  teeth  of  Orycterocetus  quadratidens 
is  the  cross  banding  of  the  dentine  which  Leidy  refers  to  as  “annular 
lines  of  growth.”  Structures  similar  to  these  are  present  in  some  of 
the  fossil  species  of  Physeter  and  allied  genera  figured  by  Van  Beneden 

1  J.  Leidy  (Observations  on  extinct  Cetacea),  Proc.  Acad.  Nat.  Sci.  Philadelphia,  vol.  6,  p. 
378,  August  1853. 

2  J.  Leidy,  The  extinct  mammalian  fauna  of  Dakota  and  Nebraska,  including  an  account  of 
some  allied  forms  from  other  localities,  together  with  a  synopsis  of  the  mammalian  remains  of 
North  America,  Journ.  Acad.  Nat.  Sci.  Philadelphia,  ser.  2,  vol.  7,  pp.  436-437,  pi.  30,  figs.  16,  17, 
1869. 


Two  Fossil  Physeteroid  Whales. 


11 


and  Gervais.1  The  peculiar  appearance  of  these  teeth,  as  figured  by 
Leidy,  is  due  to  the  loss  of  the  cement  which  encircles  the  longi¬ 
tudinal  axis  of  dentine.  According  to  Leidy’s  measurements  for  the 
fragment  of  the  maxilla  and  alveoli  of  Orycterocetus  quadratidens, 
there  is  little  difference  in  size  between  it  and  the  corresponding 
portion  of  the  maxilla  in  the  skull  of  the  type  of  mediatlanticus.  The 
vertical  depth  of  the  maxilla  of  the  St.  Marys  physeteroid,  as  meas¬ 
ured  from  the  premaxillary  suture  to  the  alveolar  row,  gradually 
increases  anteriorly  and  at  the  level  of  the  first  alveolus  measures 
75  mm.  The  alveoli  average  about  an  inch  in  diameter  at  the  surface 
and  the  sockets  are  not  more  than  2  inches  deep.  The  fragment  of 
the  maxilla  described  by  Leidy  was  about  8  inches  long  and  contained 
the  same  number  of  alveoli.  In  all  probability  it  represented  a 
section  of  the  rostrum,  corresponding  in  part  to  that  which  is  missing 
from  Cope’s  type.  Both  specimens  were  obtained  from  nearby  Upper 
Miocene  formations.  Although  the  exact  locality  in  Virginia  from 
which  the  original  material  representing  Orycterocetus  quadratidens 
was  obtained  may  never  be  ascertained,  it  seems  probable  that  this 
species  at  least  did  bear  some  resemblance  to  the  St.  Marys  physe¬ 
teroid,  and  for  this  reason  the  latter  may  tentatively  be  known  as 
Orycterocetus  mediatlanticus  (Cope). 

Originally,  Leidy  referred  Orycterocetus  quadratidens  to  the  Del- 
phinidae,  but  in  1869  he  was  inclined  to  regard  it  as  related  to  the 
sperm  whale.  In  1890,  Cope  actually  referred  the  species  to  Physeter, 
while  Professor  Abel  in  1905  regarded  the  teeth  of  this  species  as 
closely  resembling,  except  in  size,  two  found  in  the  Upper  Miocene 
formation  of  the  Antwerp  basin  which  he  thought  might  belong  to 
the  physeteroid  genus  Thalassocetus  established  by  him  on  a  portion 
of  a  skull  from  the  same  formation. 

There  is  another  North  American  Upper  Miocene  pelagic  mammal 
which  should  be  considered  in  the  present  discussion,  and  that  is 
Ontocetus  emmonsi  of  Leidy.2  This  fossil  mammal  has  been  referred 
to  the  Physeteridae,  but  all  that  is  known  concerning  it  consists  of  a 
single,  large,  somewhat  mutilated  tooth  from  the  Miocene  of  North 
Carolina.  The  type  locality,  formation,  and  present  whereabouts 
of  this  specimen  are  unknown.  According  to  Leidy,  this  tooth  is 
curved,  laterally  compressed,  and  fluted.  When  perfect  it  measured 
10  or  more  inches  in  length,  about  4  inches  in  an  anteroposterior 
direction,  and  approximately  2.5  inches  transversely.  The  dimen¬ 
sions  of  the  tooth,  as  will  be  observed,  are  similar  to  those  of  large 
teeth  of  Physeter  catodon,  but  the  curvature  is  more  pronounced.  It 
also  exhibits  certain  transverse  markings  which  resemble  those  on 

1  P.  J.  Van  Beneden  and  P.  Gervais,  Osteographie  des  C6tac6s  vivants  et  fossiles,  Paris,  pi. 
20,  1880. 

s  J.  Leidy  (Remarks  on  Dromatherium  sylvestre  and  Ontocetus  emmonsi),  Proc.  Acad.  Nat. 
Sci.  Philadelphia,  vol.  11,  p.  162,  1859. 


12  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


fossil  teeth  assigned  to  Physeter  and  allied  genera.  None  of  these 
teeth,  however,  whether  recent  or  fossil,  have  the  cement  fluted  to 
any  appreciable  extent,  so  far  as  known.  This  fluting  may  have 
influenced  Leidy  when  he  advanced  the  opinion  that  Ontocetus  might 
be  allied  to  the  walrus.  This  is  not  impossible,  but  the  tusks  of 
Odobenus  are  comparatively  straight,  while  this  tooth  may  have  been 
curved. 

An  entirely  different  view  was  advanced  by  Cope1  who,  in  1869, 
remarks  that  the  tooth  of  Ontocetus  belongs  to  a  large  sirenian  allied 
to  Halicore.  It  is  not  probable  that  this  view  is  correct,  for  the 
reason  that  sirenian  canines  are  either  coated  with  enamel  on  all 
sides,  or  on  the  front  and  sides.  There  is  no  evidence  that  the  tooth 
of  Ontocetus  was  thus  covered,  though  it  may  have  been  when 
perfect.  The  annular  lines  mentioned  by  Leidy  are  observable  on 
teeth  of  Physeter  and  Orycterocetus.  It  should  be  noted,  however, 
that  the  longitudinal  fluting  of  the  surface  of  the  tooth  of  Ontocetus 
already  alluded  to,  suggests  a  similar  conformation  in  Halicore  and 
other  sirenians.  This,  perhaps,  is  the  characteristic  which  is  most 
suggestive  of  sirenian  relationship,  unless  the  central  accumulation 
of  osteodentine  be  so  regarded.  The  tooth  possessed  a  comparatively 
thin  coat  of  cementum,  in  which  respect  it  differs  from  teeth  of  fossil 
and  of  adult  living  sperm  whales,  though  agreeing  with  them  in  that 
the  interior  was  built  up  with  a  large  amount  of  osteodentine. 

On  referring  to  Emmons’s  figure2  of  this  tooth,  it  seems  probable 
that  Ontocetus  emmonsi  represents  some  cetacean  allied  to  the  sperm 
whale,  but  until  additional  specimens  have  been  obtained  its  relation¬ 
ships  are  likely  to  remain  in  doubt.  Taking  into  consideration 
Leidy’s  statement  that  the  cement  on  this  tooth  is  comparatively 
thin  and  the  general  appearance  of  the  tooth  as  figured  by  Emmons, 
it  appears  that  the  longitudinal  fluting  which  has  caused  so  much 
discussion  is  due  in  part  to  erosion  and  in  part  to  the  entire  absence 
of  cement  in  places.  Similar  fluting  has  been  observed  by  the  writer 
on  the  dentinal  axes  of  other  large  physeteroid  teeth.  The  external 
coat  of  cement  which  encircles  the  dentinal  axis  is  usually  thick  and 
conceals  this  fluting  when  present.  Teeth  similar  in  size  and  general 
appearance  to  Ontocetus  emmonsi  are  present  in  both  jaws  of  a  fossil 
physeteroid  from  the  Miocene  of  Santa  Barbara  County,  California. 

A  review  of  the  known  fossil  and  living  physeter oids  reveals  the 
fact  that  they  may  be  divided  into  two  more  or  less  clearly  marked 
groups,  those  with  long  rostra,  no  sagittal  crest,  rise  of  anterior 

1  E.  D.  Cope,  Synopsis  of  the  extinct  Mammalia  of  the  cave  formations  in  the  United  States, 
with  observations  on  some  Myriopoda  found  in  and  near  the  same,  and  on  some  extinct  mammals 
of  the  caves  of  Anguilla,  W.  I.,  and  of  other  localities,  Proc.  Amer.  Philos.  Soc.,  Philadelphia,  vol. 
11,  p.  190,  1869. 

2  E.  Emmons,  Manual  of  geology,  2d  ed.,  text-fig.  187  (lower  figure)  on  p.  219  [figure  of  type 
tooth,  0.5  nat.  size]. 


Two  Fossil  Physeteroid  Whales. 


13 


border  of  lateral  wall  of  supracranial  basin  within  antorbital  notch, 
small  lachrymals,  elongate  jugals  with  long  styliform  processes,  small 
pterygoids,  expanded  palatines,  and  large  infraorbital  foramina,  and 
those  with  short  rostra,  well-developed  sagittal  crest,  rise  of  anterior 
border  of  lateral  wall  of  supracranial  basin  outside  of  antorbital 
notch,  large  thickened  lachrymals,  jugals  with  very  short  styliform 
processes,  expanded  pterygoids,  small  palatines,  and  small  infra¬ 
orbital  foramina.  To  the  first  family,  the  Physeteridae,  the  following 
genera  are  referred :  Diaphorocetus,  Idiophyseter,  Iaiorophus,  Ontocetus, 
Orycterocetus ,  Physeter,  Physeterula,  Scaldicetus,  Thalassocetus;  the 
second  family,  the  Kogiidae,  is  represented  by  the  living  genus  Kogia. 

Key  to  Skulls. 

A1.  Rostrum  strongly  constricted  from  side  to  side  mesially. 

B1.  Lateral  margin  of  maxilla  excessively  thickened  at  level  of  supraorbital 
process  of  frontal;  rise  of  anterior  border  of  supracranial  basin  is 
within  antorbital  notch  and  not  without  as  in  Kogia ,  and  gradu¬ 
ally  attains  a  considerable  elevation  immediately  in  front  of 
temporal  fossa  and  a  little  within  vertical  plane  of  supraorbital 
border;  external  border  of  maxilla  rolls  over  the  underlying 
frontal  above  the  temporal  fossa  and  the  longitudinal  thicken¬ 
ing  of  the  former  marks  the  lateral  boundary  of  the  supracran¬ 
ial  basin;  size  large. 

b1.  A  large  foramen  (the  orifice  looking  upward  and  connecting  with  the 
infraorbital  system)  pierces  the  maxilla  some  113  mm.  above  the 
large  maxillary  incisure  on  the  anterior  margin  of  the  rising 
lateral  wall  of  the  supracranial  basin;  a  large  maxillary  foramen 
between  antorbital  notch  and  nasal  passage  on  rising  edge  of 
supracranial  basin,  but  situated  below  level  of  incisure;  a  smaller 
one  at  the  same  level,  just  posterior  and  internal  to  it;  a  longitu¬ 
dinal  groove  leading  from  the  inferior  maxillary  foramen 
and  directed  almost  obliquely  forward  is  pierced  in  its  fundus 
by  another  foramen;  in  front  of  this  groove  is  a  wide  depressed 
orifice  of  still  another  foramen  which  pierces  the  maxilla  close 
to  its  premaxillary  border;  a  large  foramen  pierces  the  max¬ 
illa  on  the  lateral  wall  of  supracranial  basin  at  level  of  nasal 
passages;  right  premaxilla  pierced  near  anterior  part  of  eth¬ 
moid  crest  by  a  large  circular  foramen;  rostrum  vaulted; 
rostral  portion  of  premaxilla  elevated;  margins  of  premaxillae 
not  in  contact  at  level  of  anterior  margin  of  ethmoid  crest ;  ant¬ 
orbital  notches  relatively  small  and  narrow;  more  than  8  alveoli 
in  each  maxilla;  maxillae  not  closely  approximated  from  a  ven¬ 
tral  view,  exposing  a  considerable  portion  of  anterior  extension 
of  vomer;  palatines  large,  horizontally  expanded,  and  not  over¬ 
ridden  to  any  marked  degree  by  pterygoids;  a  single  ventral 
infraorbital  orifice  bounded  internally  by  palatine  and  exter¬ 
nally  by  maxilla;  length  of  rostrum  800+  mm.;  elevation  of 
lateral  crest  of  supracranial  basin  above  orbit,  apex  broken  off, 

310  mm.;  length  of  rostral  fragment  on  middle  line  800  mm.; 
breadth  of  rostrum  at  antorbital  notches,  estimated  710  mm.; 
breadth  of  extremity  of  rostrum  at  point  where  broken  off  172 
mm.  (See  pis.  4,  5.) . Orycterocetus  mecLiatlanticus  (Cope). 


14  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


B2.  Lateral  margin  of  maxilla  not  excessively  thickened  at  level  of  supra¬ 
orbital  process  of  frontal. 

Cl.  As  many  as  24  teeth  in  each  mandible. 
b2.  A  large  foramen  (the  orifice  looking  upward  and  connecting  with  the 
infraorbital  system)  pierces  the  maxilla  on  the  summit  of  the 
lateral  crest  of  the  supracranial  basin  above  the  orbit;  a  large 
maxillary  incisure  between  antorbital  notch  and  nasal  passage 
on  anterior  rising  edge  of  supracranial  basin;  a  much  smaller  one 
internal  and  slightly  below  it  (the  two  foramina  almost  con¬ 
fluent)  ;  a  small  foramen  below  and  anterior  to  large  maxillary 
foramen,  but  without  longitudinal  groove  as  in  Orycterocetus; 
a  minute  foramen  situated  mesially  and  anterior  to  all  of  the 
above-mentioned  foramina;  and  still  another  small  depressed 
foramen  which  pierces  the  maxilla  on  its  premaxillary  border; 
portion  of  premaxilla  which  is  pierced  by  a  foramen  apparently 
missing;  rostrum  vaulted;  inner  margins  of  premaxillae  in  con¬ 
tact  anteriorly,  completely  roofing  mesorostral  gutter;  pre¬ 
maxilla  arched  or  elevated  anteriorly;  antorbital  notches  rela¬ 
tively  small  and  rounded;  a  small  antorbital  process  of  the 
maxilla;  premaxilla  projecting  anteriorly  beyond  maxilla;  ex¬ 
ternal  margin  of  maxilla  relatively  thin  in  front  of  antorbital 
notch,  but  further  forward  this  thin  margin  disappears  in  con- 
quence  of  its  downward  curvature  and  the  lateral  compression 
of  the  extremity  of  the  rostrum;  22  teeth  in  upper  jaw,  3  of 
which  are  inserted  in  premaxilla;  24  teeth  in  mandible;  teeth 
large,  long  (slightly  more  than  100  mm.),  terete,  slightly  curved, 
and  cylindrical  in  section;  enamel  on  crowns  finely  striated 
longitudinally;  crowns  of  teeth  conical,  about  32  mm.  long; 
length  of  rostrum  about  1,240  mm.;  elevation  of  lateral  crest 
of  supracranial  basin  above  orbit  about  175  mm.;  total  length, 
as  preserved,  about  1,600  mm.;  breadth  of  rostrum  at  antorbital 
notches  about  650  mm . Idiorophus  patagonicus  (Lydekker). 

C2.  Not  more  than  20  teeth  (so  far  as  known)  in  each  mandible. 

b3.  Occiput  abruptly  truncated;  size  large,  total  length  of  skull  more 
than  1,000  mm.;  a  large  foramen  (the  orifice  looking  upward  and 
connecting  with  the  infraorbital  system)  pierces  the  maxilla 
on  the  rising  lateral  wall  of  the  supracranial  basin  at  the  level 
of  the  orbit;  the  large  maxillary  incisure  is  probably  situated 
between  antorbital  notch  and  nasal  passage  as  there  is  a  notch 
at  that  point  on  broken  border  of  right  maxilla;  external  border 
of  maxilla  does  not  roll  over  underlying  frontal  above  temporal 
fossa,  but  instead  marks  the  lateral  boundary  of  the  supracranial 
basin;  rostrum  not  sufficiently  well  known  for  diagnosis;  pre¬ 
maxillae  flattened  anterior  to  nasal  passages;  inner  margins  of 
premaxillae  not  in  contact  at  level  of  anterior  margin  of  ethmoid 
crest;  antorbital  notches  small;  a  distinct  antorbital  process  of 
the  maxilla;  zygomatic  processes  narrowing  anteriorly,  pointed; 

20  alveoli  in  each  mandible;  teeth  measure  from  50  to  130  mm. 
in  length;  maximum  thickness  of  largest  teeth  about  30  mm.; 
enamel  not  present  on  crowns  of  teeth;  mandibular  teeth  worn 
on  superior  and  posterior  surfaces,  from  which  it  is  inferred  that 
teeth  were  present  in  upper  jaw;  occipital  face  of  skull  slightly 
rounded;  length  of  rostrum,  as  estimated,  1,000 ±  mm.;  eleva¬ 
tion  of  lateral  crest  not  known;  total  length  of  skull,  estimated, 


Two  Fossil  Physeteroid  Whales. 


15 


1,350  ±  mm.;  breadth  of  skull  across  supraorbital  processes, 
estimated,  705  mm . Physeterula  dubusii  Van  Beneden. 

b4.  Occiput  obliquely  truncated;  size  medium,  total  length  of  skull  less 
than  700  mm.;  a  small  foramen  (the  orifice  looking  upward  and 
connecting  with  the  infraorbital  system)  pierces  the  maxilla 
on  the  summit  of  the  lateral  crest  of  the  supracranial  basin  be¬ 
hind  the  orbit;  maxillary  foramina  opening  into  a  slit-like 
incisure  in  maxilla  between  antorbital  notch  and  nasal  passage, 
and  situated  posterior  to  antorbital  notch;  external  border  of 
maxilla  rolls  over  the  underlying  frontal  above  the  temporal 
fossa,  and  the  longitudinal  thickening  of  the  former  marks 
the  lateral  boundary  of  the  supracranial  basin;  rostrum  com¬ 
pressed  dorso-ventrally;  premaxillae  flattened  or  depressed 
anteriorly;  inner  margins  of  premaxillae  in  contact  at  level  of 
anterior  margin  of  ethmoid  crest;  antorbital  notches  deep 
and  narrow;  a  distinct  antorbital  process  of  the  maxilla;  supra¬ 
orbital  process  shallow;  postnarial  process  of  premaxilla 
broad,  forming  medial  surface  of  posterior  wall  of  supracranial 
basin;  a  large  premaxillary  foramen  in  right  premaxilla  situated 
anterior  to  antorbital  notches;  mesorostral  gutter  broad;  occi¬ 
pital  face  of  skull  somewhat  flattened,  not  produced  beyond 
level  of  posterior  borders  of  exoccipitals  and  zygomatic  pro¬ 
cesses,  although  portions  of  the  condyles  do  project;  zygoma 
narrow,  attenuated,  and  pointed  anteriorly;  lachrymal  not 
extending  inw^ard  beyond  ventral  infraorbital  orifice;  more 
than  13  alveoli  in  maxilla;  teeth  not  described;  18  or  19  alveoli 
in  each  mandible;  length  of  rostrum,  estimated  380+  mm.; 
total  length  of  skull  as  preserved  582  mm.;  breadth  of  rostrum 
at  antorbital  notches  244+  mm . Diaphorocetus  poucheti  (Moreno). 

A2.  Rostrum  not  strongly  constricted  from  side  to  side  mesially  (so  far  as 
known) . 

B3.  Size  medium  or  small  (skulls,  so  far  as  known,  not  exceeding  3  feet  in 
length). 

C3.  Distance  between  outer  margins  of  condyles  more  than  one-third  of  breadth 
of  skull  across  supraorbital  processes  of  frontals;  occipital  face 
of  skull  rounded;  inner  margins  of  premaxillae  in  contact  at  level 
of  anterior  margin  of  ethmoid  crest;  mesorostral  gutter  broad; 
supraorbital  process  moderately  thick;  superior  face  of  supra¬ 
orbital  process  sloping  obliquely  downward,  posterior  and  exter¬ 
nal  borders  concave;  maxilla  thin  above  orbit,  with  character¬ 
istic  antorbital  notch  and  longitudinal  thickening  posterior  to 
maxillary  incisure  and  along  lateral  wall  of  supra-cranial  basin; 
maxillary  canal  opening  into  a  slit-like  incisure  as  in  Physe- 
ter;  a  large  foramen  in  right  premaxilla  situated  anterior  to  max¬ 
illary  incisure;  rostral  portion  of  premaxilla  flattened  or  de¬ 
pressed;  supracranial  basin  large,  walls  descend  abruptly; 
cranium  asymmetrical;  postnarial  process  of  premaxilla  broadly 
expanded,  forming  about  two-thirds  of  posterior  wTall  of  basin; 
occiput  abruptly  truncated;  rostrum  not  constricted  from  side 
to  side  mesially;  more  than  four  alveoli  in  each  maxilla;  lachry¬ 
mal  not  extending  inward  beyond  infraorbital  orifices;  palatines 
small,  narrow,  and  overridden  posteriorly  by  pterygoids;  a  pair 
of  ventral  infraorbital  orifices  on  each  side;  palatal  surface  of 


16 


Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


maxillae  depressed  laterally,  forming  a  median  ridge  in  front  of 
palatines;  most  of  vomer  concealed  from  a  ventral  view  by  close 
approximation  of  maxillae,  the  axial  ridge  alone  being  visible; 
more  than  4  alveoli  in  each  maxilla ;  alisphenoids  large ;  total  length 
of  skull  as  preserved  615  mm.;  breadth  of  rostrum  at  antorbital 
notches,  estimated  368  mm . Idiophyseter  merriami  gen.  and  sp.  new. 

C4.  Distance  between  outer  margins  of  condyles  certainly  less  than  one-third  of 
breadth  of  skull  across  supraorbital  processes  of  frontals. 

c1.  Estimated  breadth  of  skull  across  supraorbital  processes  550 ±  mm.; 

inner  margins  of  premaxillae  almost  in  contact  at  level  of  ante¬ 
rior  margin  of  ethmoid  crest,  a  wide  interspace  opposite  premax¬ 
illary  foramen,  and  from  this  point  anteriorly  the  inner  margins 
of  the  premaxillae  gradually  converge;  rostrum  long,  dorso-ven- 
trally  compressed,  tapering  anteriorly,  but  not  noticeably  con¬ 
stricted;  supraorbital  region  not  known;  posterior  borders  of 
maxillary  incisures  apparently  on  a  line  with  anterior  borders  of 
nasal  passages;  occipital  face  of  skull  flattened,  not  produced 
beyond  level  of  posterior  margins  of  exoccipitals  and  zygomatic 
processes,  although  the  condyles  do  project  posteriorly;  a  large 
foramen  in  left  premaxilla  anterior  to  antorbital  notches;  a 
rather  large  foramen  in  right  maxilla  close  to  premaxillary  bor¬ 
der  and  immediately  in  front  of  anterior  margin  of  ethmoid 
crest;  only  twro  teeth  in  place  but,  judging  from  width  of  inter¬ 
vals  between  alveoli,  the  number  of  teeth  in  each  maxilla  may 
equal  19  and  in  premaxilla  3  or  4;  teeth  of  young  individuals 
elongated,  nearly  terete,  with  rather  short  crowns  which  are 
coated  with  longitudinally  striated  enamel;  teeth  of  old  individ¬ 
uals  with  well-marked  constriction  between  base  of  crown  and 
root,  with  the  latter  gibbous  near  middle,  and  with  enamel 
on  crown  striated  longitudinally;  length  of  tooth  88  mm.,  of 
which  the  crown  measures  11  mm.1;  total  length  of  skull  as  pre¬ 
served  812  =b  mm . Scaldicetus  rnortezelensis  (Du  Bus). 

c2.  Estimated  breadth  of  skull  across  supraorbital  processes  320  mm.;  su¬ 
praorbital  processes  of  frontals  not  completely  overridden  by 
maxillae  (breadth  of  border  not  covered  by  maxilla  20  mm.); 
superior  face  of  supraorbital  process  oblique,  characterized  by 
the  steep  slope;  posterior  and  ventral  borders  of  this  process 
are  concave;  postorbital  projection  rather  long,  pointed; 
maxilla  relatively  thin  above  orbit,  with  characteristic  antorbi¬ 
tal  notch,  and  with  longitudinal  thickening  posterior  to  maxil¬ 
lary  incisure  along  lateral  wall  of  supracranial  basin;  an  antor¬ 
bital  process  of  maxilla;  infraorbital  canal  apparently  opening 
into  a  slit-like  incisure  in  maxilla  as  in  a  young  Physeter;  supra¬ 
cranial  basin  large,  with  a  steep  slope  to  walls;  cranium  asym¬ 
metrical,  strongly  warped  toward  left  side;  bones  on  right  side  of 
basin  constitute  approximately  two-thirds  of  breadth  of  brain- 
case;  postnarial  process  of  premaxilla  resembling  that  of  Idio- 
physeier;  occiput  abruptly  truncated ;  parietals  visible  on  vertex 
as  a  narrow  plate  inserted  between  supraoccipital  and  frontals; 
zygomatic  process  very  small;  articular  surface  (glenoid  fossa) 
triangular,  not  strongly  excavated . Thalassocetus  antwerpiensis  Abel. 

1  The  teeth  of  Scaldicetus  grandis  measure  from  85  to  140  mm.  in  length  and  those  of  Scaldicetus 

carelti  from  140  to  260  mm. 


Two  Fossil  Physeteroid  Whales. 


17 


B4.  Size  large  (skulls  of  adult  males  attaining  a  length  of  16  feet  or  more); 

breadth  of  rostrum  at  middle  about  three-fourths  of  that  at 
base;  distance  between  outer  margins  of  condyles  about  one- 
tenth  of  breadth  of  skull  across  supraorbital  processes. 
b1.  A  large  passage  (connecting  with  the  infraorbital  system)  opening  into 
a  slit-like  incisure  in  maxilla  between  antorbital  notch  and 
nasal  passage;  foramen  in  right  premaxilla  situated  posterior 
to  maxillary  incisure  in  skulls  of  adults  and  in  front  of  the  same 
in  young;  rostrum  very  broad  for  its  length,  and  depressed  or 
excavated  from  above;  rostral  portion  of  premaxilla  flattened; 
mesorostral  gutter  exposed  for  most  of  its  length;  extremities  of 
premaxillae  projecting  beyond  maxillae;  cranium  asymmetrical; 
a  large  supracranial  basin  with  abruptly  descending  walls; 
lateral  border  of  maxilla  somewhat  elevated  at  the  level  of 
the  supraorbital  process;  antorbital  notches  deep  and  narrow; 
postnarial  process  broader  than  rest  of  right  premaxilla;  occi¬ 
put  abruptly  truncated;  occipital  condyles  relatively  small; 
alveolar  groove  continuous,  no  septa,  and  no  permanent  teeth 
in  upper  jaw;  27  teeth  in  each  mandible;  zygoma  complete; 
lachrymal  extending  inward  to  or  beyond  infraorbital  orifice; 
palatines  large,  expanded  horizontally,  and  overridden  poste¬ 
riorly  and  mesially  by  the  pterygoids;  inner  margins  of  maxillae 
not  in  contact  from  a  ventral  view,  thus  exposing  axial  ridge  of 
the  vomer  anterior  to  palatines . Physeter  catodon  Linnaeus. 

The  influence  which  the  developing  fat  or  spermaceti  cushion 
has  exerted  in  modifying  the  appearance  of  the  skull  is  more  evident 
in  the  living  genus  Physeter  than  in  the  Lower  Miocene  genera 
Idiorophus  and  Diaphorocetus.  Even  in  these  Lower  Miocene  genera, 
this  cushion  had  profoundly  altered  the  appearance  of  the  dorsal 
surface  of  the  braincase,  as  is  shown  by  the  presence  of  a  large  supra¬ 
cranial  basin.  The  roof  of  the  braincase  seems  to  have  been  depressed 
below  its  original  level  by  this  additional  weight.  The  culmination 
of  this  tendency  toward  the  abnormal  development  of  a  spermaceti 
cushion  may  be  observed  in  the  living  genus  Physeter ,  the  size  of 
whose  skull  is  disproportionate,  both  in  respect  to  the  brain  and  to 
the  body.  In  this  genus,  the  spermaceti  cushion  has  attained  a  great 
size  and,  in  correlation  with  this  increase,  the  bones  comprising  the 
rostrum  have  expanded  horizontally.  With  the  development  of  the 
supracranial  basin,  the  frontals  were  depressed  along  the  median 
line,  one  nasal  bone  was  lost,  and  the  left  nasal  passage  greatly 
enlarged.  Along  with  these  asymmetrical  modifications,  there  has 
been  a  corresponding  development  of  a  massive  skull  with  ponderous 
bones  to  support  the  great  weight  of  the  spermaceti  cushion  and  to 
counteract  the  resistance  of  the  water.  The  posterior  margin  of  the 
facial  depression  is  more  abruptly  elevated  than  in  any  other  family 
of  cetaceans,  and  the  basin  extends  farther  backward.  In  the  upper 
jaw,  the  teeth  have  become  atrophied  in  the  genus  Physeter  and  are 
hidden  in  the  gum. 


18  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


From  the  foregoing,  it  will  become  apparent  that  there  are  a 
number  of  as  yet  unknown  fossil  types  to  explain  the  course  of  some 
of  these  modifications;  hence  the  description  of  these  California 
physeteroids  may  afford  additional  data  for  the  evolutionary  history 
of  this  family. 

Through  the  courtesy  of  Professor  B.  L.  Clark  and  Mr.  E.  L. 
Furlong,  the  writer  was  given  permission  to  describe  the  cetacean 
material  in  the  Palaeontological  Museum  of  the  University  of 
California.  The  writer  also  takes  this  opportunity  to  thank  Dr. 
John  C.  Merriam  and  the  Carnegie  Institution  of  Washington  for 
the  support  which  has  made  this  study  possible.  For  the  privilege  of 
studying  the  fossil  and  living  cetaceans  in  the  United  States  National 
Museum  I  am  indebted  to  Mr.  C.  W.  Gilmore  and  Mr.  Gerrit  S. 
Miller  jr.,  curators  of  their  respective  departments.  The  drawings  of 
the  specimens  herewith  given  were  carefully  executed  by  Mrs. 
Freida  Abernathy  and  nearly  every  character  described  or  figured 
has  been  corroborated  by  comparison  with  skulls  of  living  and  fossil 
cetaceans,  as  well  as  with  the  published  figures  and  descriptions  of 
European  specimens. 

Idiophyseter  merriami,  new  genus  and  species. 

Type  specimen. — Cat.  No.  24287,  Museum  of  Palaeontology,  University  of  Calif- 
fornia.  The  type  consists  of  an  imperfect  skull;  the  jugals,  periotics,  tympanies, 
extremity  of  the  rostrum,  and  the  zygomatic  processes  are  missing.  The  maxillae, 
premaxillae,  and  pterygoids  are  imperfectly  preserved. 

Type  locality. — The  occurrence  is  as  follows:  Near  latitude  35°  33'  40"  North  and 
longitude  120°  48'  32"  West,  near  the  town  of  Templeton,  San  Luis  Obispo  County, 
California.  Section  29,  Range  11  East,  Township  27  South,  Adelaida  Quadrangle, 
U.  S.  Geological  Survey. 

Horizon. — The  specimen  was  discovered  and  excavated  by  Mr.  Joseph  Walker  in  the 
fall  of  1920.  It  was  found  embedded  in  a  stratum  of  clay  which  was  exposed  at  the 
bottom  of  a  deep  ravine.  Some  of  the  matrix  was  submitted  to  Dr.  G.  P.  Merrill, 
head  curator,  Department  of  Geology,  United  States  National  Museum,  and  he  reports 
that  it  is  an  aluminous  clay  and,  judging  from  the  character  of  the  decomposition 
products,  derived  from  volcanic  detritus  of  an  andesitic  nature.  The  deposits  in  this 
region  appear  to  be  equivalent  in  time  to  the  Temblor  formation  of  the  Middle  Miocene. 

One  distinguishing  feature  of  this  fossil  skull,  as  compared  with  skulls  of  adults  of 
Physeter,  is  its  relatively  small  size.  A  skull  of  a  foetus  in  the  United  States  National 
Museum  measures  851  mm.  in  length  and  this  is  slightly  larger  than  this  fossil  speci¬ 
men.  Skulls  of  adult  males  of  Physeter  are  known  which  measure  at  least  16  feet  in 
length.  Because  of  many  corresponding  features,  it  will  be  advisable  to  compare  this 
fossil  skull  chiefly  with  Physeter ,  adults  of  which  are  the  largest  known  physeteroids. 
Comparison  will  also  be  made  with  the  Pigmy  Sperm  whale,  Kogia. 

Skull. 

DORSAL  VIEW. 

The  anterior  extremity  of  the  rostrum  was  not  found  and,  although  the  restoration 
(pi.  1,  fig.  1)  is  in  accordance  with  the  curvature  of  that  portion  of  the  outer  surface  of 
the  right  maxilla  which  is  preserved,  it  is  possible  that  the  rostrum  originally  may  have 
been  somewhat  longer.  The  slope  of  the  outer  face  of  the  right  maxilla  suggests  a 
short  rostral  type  like  that  found  in  Kogia  rather  than  the  more  elongate  type  of  Phy- 


Two  Fossil  Physeteroid  Whales 


19 


seter.  Granting  the  correctness  of  the  rostrum  as  restored,  there  is  still  a  slight  dis¬ 
parity  between  the  relative  anterior  extension  of  the  maxillae  and  premaxillae,  and  the 
same  elements  in  the  skulls  of  Physeter  and  Kogia.  Measuring  from  the  level  of  the 
antorbital  notches  in  the  young  Physeter  skull  gives  a  relative  proportion  of  lengths 
between  the  rostral  and  cranial  portions  of  the  skull  as  12  :  9.  In  Kogia  the  rostrum 
has  become  relatively  shortened,  a  distinctive  feature  of  the  specialized  Kogiidae,  the 
proportional  lengths  being  as  9  :  9.  The  proportional  lengths  of  the  rostrum  and 
cranium  of  this  fossil  skull  as  restored  are  also  9  :  9. 


Fig,  1. — Dorsal  view  of  type  skull  of  Idiophyseler  merriami.  Cat.  No.  24287, 
Palaeont.  Mus.,  Univ.  Calif.  Ant.  n.,  antorbital  notch;  C.,  con¬ 
dyle;  Elh.,  ethmoid;  Ex.  oc.,  exoccipital;  Fr.  frontal;  L.  cr.  max., 
lateral  crest  of  maxilla;  Max.,  maxilla;  Max.  /.,  maxillary  fora¬ 
men;  N.  A.,  nasal  passage;  Pa.,  parietal;  Pmx.,  premaxilla; 

Pmx.  /.,  premaxillary  foramen;  S.  oc.,  supraoccipital;  Sq., 
squamosal;  Vo.,  vomer. 

This  aspect  of  the  skull  (text-fig.  I)  is  interesting  because  it  tends  to  confirm  the 
allocation  given  above.  Skulls  of  Kogia  are  characterized  by  a  prominent  sagittal 
crest  between  the  nares  and  the  vertex,  while  this  crest  is  lacking  on  those  of  Physeter, 
and  the  supracranial  basin  is  greatly  developed.  The  curvature  and  outlines  of  those 


20  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


elements  which  are  preserved  afford  a  basis  for  computing  and  restoring  the  original 
outlines  of  the  skull.  In  this  restoration,  some  allowance  must  be  made  for  possible 
differences  in  the  degree  of  elevation  or  projection  of  the  free  edge  of  the  maxilla  above 
the  maxillary  foramina.  With  this  exception,  the  relations  and  peculiarities  of  the 
various  bones  comprising  the  dorsal  face  of  the  braincase  of  this  fossil  skull  are 
essentially  the  same  as  in  the  Physeter  skull. 

The  maxillae  are  the  very  large  and  massive  bones  which  form  the  major  portion  of 
the  rostrum  and  whose  ascending  processes  slide  backward  over  the  upper  surfaces  of 
the  supraorbital  plates  of  the  frontals.  They  expand  in  width  in  front  of  the  deep 
antorbital  notches.  Their  flat  upper  surfaces  are  formed  by  a  thin  outer  plate  of 
dense  bone,  but  the  internal  structure  is  cancellous  as  in  Physeter ,  with  distinct  cells 
which  were  probably  filled  with  oil  in  life  as  in  the  latter.  On  the  dorsal  surface  there 
is  a  broad  groove  leading  forward  from  the  maxillary  incisure.  The  internal  margin  of 
each  maxilla  embraces  the  corresponding  border  of  the  premaxilla.  Judging  from  the 
section  of  the  right  maxilla  which  is  preserved,  there  are  but  slight  differences  in  con¬ 
tour  as  well  as  in  relative  proportions  from  Physeter.  The  lateral  border  of  the  maxilla 
is  thick  anteriorly,  but  as  the  maxilla  approaches  the  antorbital  notches,  in  consequence 
of  the  upward  slope  of  the  ventral  surface  from  the  median  line,  it  becomes  progressively 
thinner,  decreasing  until  it  is  less  than  half  of  its  maximum  depth,  and  at  the  widest 
point  probably  exhibiting  a  tendency  to  curve  downward. 

As  seen  from  dorsal  view,  the  median  portion  of  the  rostrum  is  formed  by  the  pre¬ 
maxillae,  in  the  shape  of  rather  broad  bands  of  varying  width  with  very  thin  edges  over¬ 
hanging  the  mesorostral  gutter,  and  by  the  anterior  extension  of  the  vomer  which 
constitutes  the  floor  of  the  gutter.  With  the  exception  of  a  short  interval  at  the  ex¬ 
tremity,  the  vomer  in  Kogia  and  Physeter  extends  the  whole  length  of  the  gutter. 
On  the  outside,  the  vomer  meets  the  inner  borders  of  the  premaxillae  laterally,  and 
internally  forms  the  floor  and  walls  of  the  gutter.  The  same  relations  are  maintained 
in  this  fossil  skull.  The  floor  of  the  mesorostral  gutter  increases  in  width  posteriorly, 
but  is  shut  off  from  the  left  nasal  passage  by  the  overspreading  left  premaxilla  as  in 
Orycterocetus. 

In  Physeter ,  the  upper  surface  of  the  cranium  (pi.  6,  fig.  1)  is  concave,  the  facial 
depression  in  which  the  fat  or  spermaceti  cushion  lies  being  limited  posteriorly  by  the 
transverse  crest  and  continued  laterally  to  the  elevated  ridges  of  the  broadly  expanded 
maxillae.  The  latter  curve  upward  and  outward  from  their  internal  borders  toward  the 
external  margin  of  the  cranium.  The  great  breadth  of  the  maxillae  in  front  of  the 
antorbital  notches  adds  another  distinctive  feature  to  the  rostrum.  Asymmetrical 
modifications  in  the  cranium  are  carried  to  an  extreme  stage  in  Physeter  and  in  this 
fossil  skull.  The  left  nasal  passage  of  this  fossil  skull  is  enormously  developed,  the 
other  reduced  in  a  corresponding  degree.  The  distortion  thus  occasioned  is  not  con¬ 
fined  to  the  bones  immediately  concerned  with  the  formation  of  the  nasal  passages,  but 
affects  the  entire  surface  of  the  great  supracranial  basin. 

On  comparing  this  fossil  skull  with  that  of  the  young  Physeter,  the  arrangement  of 
the  various  bones  was  found  to  be  essentially  the  same.  Most  of  the  left  side  of  this 
skull  is  lost.  On  the  right  side  the  supraorbital  process  of  the  frontal  is  imperfect  and 
portions  of  the  outer  margin  of  the  maxilla  are  missing.  The  great  semicircular  wall 
which  rises  behind  the  nasal  passages  to  form  the  supracranial  basin  is  constituted  by 
the  thin  plate-like  posterior  extremities  of  the  premaxillae,  the  maxillae,  the  nasal, 
and  by  the  underlying  frontals.  On  the  right  side  of  the  skull,  the  greatly  thickened 
and  sloping  lateral  edges  of  the  crest  are  formed  by  the  maxilla,  but  this  bone  appar¬ 
ently  does  not  meet  the  opposite  one  in  the  middle  line.  The  internal  border  of  the 
maxilla  is  very  thin.  No  especial  asymmetry  is  presented  by  either  of  the  maxillae. 
The  maxillary  foramen  is  represented  by  a  fissure  placed  between  the  nasal  passages 
and  the  antorbital  notch,  but  nearer  the  latter,  and  into  which  a  pair  of  passages  from 
the  infraorbital  system  opens.  This  incisure  gives  passage  to  the  great  branches  of 


Two  Fossil  Physeteroid  Whales. 


21 


the  trigeminal  nerve  which  supply  the  upper  lip  and  face.  A  thin  lamina  projecting 
upward  and  outward  from  the  maxilla  on  the  internal  side  in  conjunction  with  the 
longitudinal  thickening  of  the  latter  on  the  outside  partially  inclosed  this  incisure 
from  above. 

Posteriorly,  the  maxilla  is  thickest  behind  the  maxillary  incisure.  The  outer  margin 
follows  the  corresponding  border  of  the  frontal  and,  with  the  possible  exception  of  the 
anterior  extremity  on  the  supraorbital  process,  does  not  project  beyond  the  latter. 
The  temporal  fossae  are  very  short.  Superiorly,  in  the  young  Physeter  skull  they  are 
roofed  over  by  the  frontals  and  the  maxillae  are  excluded  from  their  borders.  In  this 
fossil  skull,  the  upper  lateral  margins  of  the  frontals  have  been  destroyed.  That  por¬ 
tion  of  the  maxilla  which  overlies  the  right  supraorbital  process  suggests  the  restoration 
which  has  been  made  for  this  structure.  The  indications  are  that  the  preorbital 
projection  of  the  maxilla  rolls  over  the  supraorbital  process  of  the  frontal  and  the  dorsal 
border  of  the  lachrymal  as  in  Physeter.  This  inference,  also,  is  indicated  by  the  curva¬ 
ture  of  the  fragment  of  the  original  surface  of  the  right  maxilla  and  by  the  direction  of 
the  longitudinal  ridge  which  parallels  the  groove  leading  backward  from  the  antorbital 
notch. 

The  premaxillae,  however,  are  dissimilar  in  form.  Anterior  to  the  antorbital 
notches,  the  premaxillae  lie  on  each  side  of  the  mesorostral  gutter  and  it  is  reasonable 
to  assume  that  they  were  more  or  less  symmetrical  in  outline.  The  right  premaxilla 
passes  backward  along  the  upper  surface  of  the  cranium  and  posterior  to  the  nasal 
passages  expands  into  a  broad,  thin  plate  applied  to  the  upper  surface  of  the  frontal  and 
overlapping  the  maxilla  along  its  outer  borders.  On  the  right  premaxilla  at  the  level 
of  the  nasal  passage  there  is  a  deep  ovoidal  depression  larger  than  the  right  nasal 
passage.  The  right  premaxilla  is  much  longer  than  the  left,  extending  posteriorly  to 
the  transverse  crest;  while  the  left,  in  Physeter  at  least,  neither  reaches  beyond  the 
nares  nor  comes  in  contact  with  the  frontal.  The  right  premaxilla  is  also  broader 
than  the  left  one,  and  the  horizontal  expansion  reaches  its  greatest  development  poste¬ 
rior  to  the  nares.  The  postnarial  process  of  the  right  premaxilla  may  have  been  in 
contact  with  the  nasal,  but  this  is  rather  unlikely.  The  left  premaxilla  as  stated  above 
is  turned  out  of  its  course  by  the  enlargement  of  the  corresponding  nasal  passage  and 
apparently  terminates  suddenly  at  the  level  of  the  posterior  margin  of  this  aperture. 
In  the  right  premaxilla,  86  mm.  in  front  of  the  nasal  passage,  there  is  an  oval  foramen, 
32  mm.  in  diameter,  leading  into  a  canal  which  is  directed  outward,  and  which  com¬ 
municates  with  the  infraorbital  system.  There  is  no  corresponding  opening  on  the 
left  side. 

On  the  left  side  of  the  young  Physeter  skull  there  is  a  large  thin  plate  of  bone  overlying 
the  frontal,  meeting  the  left  maxilla  along  its  external  margin  and  extending  forward 
to  the  ethmoid,  which  appears  to  be  the  nasal.  No  trace  of  a  nasal  can  be  found  on  this 
fossil  skull,  for  the  corresponding  region  is  eroded. 

In  an  adult  Physeter  skull,  the  left  nasal  passage  is  approximately  a  foot  in  diameter 
and  in  the  young  specimen  it  measures  85  mm.  In  this  fossil  skull  it  is  approximately 
60  mm.  The  left  passage  is  also  considerably  larger  than  the  right.  The  upper  margin 
of  the  left  nasal  passage  is  formed  by  the  vomer  on  the  inner  side,  the  premaxilla  in 
front,  on  the  outer  side,  and  on  the  back,  and  postero-internally  by  a  rough  spongy  mass 
growing  out  from  the  left  side  of  the  ethmoid  which  is  twisted  over  to  the  left  side. 
Interiorly  the  vomer  curves  around  the  back  of  each  passage,  while  the  pterygoid  forms 
the  remainder  of  the  inferior  border.  In  the  anterior  and  outer  wall,  a  small  slip  of  the 
palatine  appears. 

The  ethmoid  is  an  irregular  mass  of  bone  which  is  placed  in  front  of  the  frontal 
fontanelle  and  which  interiorly  is  continuous  with  the  presphenoid.  The  latter  is 
embraced  in  the  narrow  groove  of  the  vomer.  Part  of  the  dorsal  margin  of  the  ethmoid 
is  missing.  No  trace  of  small  foramina  which  would  afford  passage  to  the  nasal 
branches  of  the  ophthalmic  division  of  the  trigeminal  nerve  can  be  found. 


22  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


From  a  dorsal  view,  the  frontals  are  almost  entirely  hidden  by  the  modifications 
which  have  resulted  from  the  development  of  the  great  supracranial  basin.  The 
posterior  and  external  borders  of  the  frontals  will  be  visible  on  a  better  preserved  skull, 
but  the  remainder  of  their  upper  surfaces  are  concealed  by  the  plate-like  posterior 
extremities  of  the  premaxillae  mesially  and  by  the  maxillae  laterally.  A  small  strip 
of  the  right  frontal  is  visible  above  the  right  nasal  passage.  Postero-mesially,  the 
frontals  are  broadly  sutured  to  the  upper  margin  of  the  supraoccipital.  Laterally,  the 
frontals  are  shut  off  from  the  supraoccipital  by  the  wedge-like  plates  of  the  parietals. 
The  supraorbital  processes  of  the  frontals  are  relatively  short  and  thick.  The  most 
obvious  peculiarity  of  this  aspect  of  the  skull  as  compared  to  that  of  the  young  Physeter 
is  the  abruptness  with  which  the  supraoccipital  descends  to  the  condyles. 

POSTERIOR  VIEW 

The  outer  borders  of  this  face  of  the  skull  (text-fig.  2)  had  been  weathered  away 
before  the  skull  was  discovered.  Computations  of  the  relative  proportions  of  the 
elements  in  a  skull  of  a  living  cetacean  when  applied  to  a  fossil  for  purposes  of  restora¬ 
tion  (pi.  3,  fig.  2)  are  always  attended  with  a  certain  amount  of  error,  but  nevertheless 
it  seems  desirable  to  make  some  attempt  in  this  direction. 


Fig.  2. — Posterior  view  of  type  skull  of  Idiophyseter  merriami.  Cat.  No.  24287, 
Palaeont.  Mus.,  Univ.  Calif.  Bo.,  basioccipital;  C.,  condyle;  Ex. 
oc.,  exoccipital;  F.  hyp.,  hypoglossal  foramen;  F.  m.,  foramen 
magnum;  J.  A.  C.,  jugulo-acoustic  canal;  S.  oc.,  supraoccipital. 

As  seen  from  the  occipital  view,  the  large  projecting  condyles  are  the  only  structures 
which  have  not  suffered  from  erosion.  The  opening  for  the  foramen  magnum  is  sub- 
triangular  in  outline.  The  condyles  are  semielliptical  in  outline,  considerably  broader 
near  the  middle  than  at  either  end,  and  slightly  convex  from  side  to  side.  They  are 
borne  on  short  condylar  processes  and  are  set  off  from  the  exoccipitals  by  shallow  con¬ 
cavities.  The  internal  margins  are  concave  and  sharply  defined,  converging  interiorly, 
but  separated  by  a  narrow  sulcus.  The  peculiarities  of  the  condyles  correspond  more 
closely  with  Physeter  than  with  Kogia.  In  Diaphorocetus  poucheti,  the  condyles  are 
relatively  smaller.  The  large  condyles,  taken  in  conjunction  with  the  broad  mastoid 
region  for  muscular  attachments,  indicate  a  certain  amount  of  mobility  for  the  head  and 
lead  further  to  the  conclusion  that  the  cervical  vertebrae  were  separate  and  not  fused. 


Two  Fossil  Physeteroid  Whales. 


23 


The  exoccipitals  were  evidently  rather  large,  coalesced  with  the  supraoccipital  above 
and  projected  outward  as  in  Physeter ,  concealing  the  zygomatic  processes  for  the  most 
part  when  viewed  from  behind.  Laterally  and  anteriorly  they  are  in  contact  with  the 
squamosals,  while  interiorly  they  are  fused  with  the  basioccipital.  The  supraoccipital 
is  broad,  with  a  low  median  carina  superiorly,  on  either  side  of  which  the  surface  is 
depressed. 

Below  the  right  condyle,  the  jugulo-acoustic  canal  is  exposed,  but  the  orifice  lies  in 
front  of  the  incisure  between  the  falcate  process  of  the  basioccipital  and  the  exoccipital. 
The  hypoglossal  foramen  pierces  the  exoccipital  and  its  ectal  orifice  may  be  seen  exter¬ 
nal  to  this  fracture  and  below  the  right  condyle. 

LATERAL  VIEW. 

In  some  respects,  the  full  extent  of  the  damage  which  has  resulted  to  this  skull  is 
more  apparent  when  viewed  from  the  side  (text-fig.  3)  than  from  any  other  aspect. 
The  zygomatic  process,  the  preorbital  and  postorbital  projections  of  the  supraorbital 
plate,  the  jugal,  and  the  projecting  processes  of  the  pterygoid  are  missing.  The  broken 
edges  of  the  exoccipital,  frontal,  and  maxilla  further  distort  this  aspect  of  the  skull. 
Even  though  the  skull  at  first  glance  may  appear  to  be  too  badly  damaged  for  accurate 
description,  such  is  really  not  the  case  for,  when  these  missing  borders  are  restored 
(pi.  2,  fig.  2),  the  fundamental  resemblances  to  Physeter  as  indicated  by  the  relations  of 
the  component  parts  become  more  apparent. 

Aside  from  whatever  uncertainty  may  exist  as  to  the  correctness  of  the  restoration, 
it  is  evident  that  this  skull  is  characterized  by  a  relatively  small  temporal  fossa.  This 
fossa  has  been  shortened  in  an  anteroposterior  direction,  and  is  bounded  by  the  frontal 
above  and  the  squamosal  below.  The  chief  point  of  interest  in  this  region  on  the  young 
Physeter  skull  (pi.  2,  fig.  1)  is  the  fate  of  the  parietal.  In  this  young  Physeter  skull,  a 
thin  T-shaped  plate  of  bone  is  inserted  in  the  vertical  interval  between  the  squamosal 
and  the  frontal,  and  also  in  the  horizontal  interval  between  the  supraoccipital  on  the 
upper  side  and  the  frontal  and  squamosal  on  the  lower.  In  more  mature  skulls,  the 
squamosal  and  frontal  unite  in  a  vertical  suture.  It  can  not  be  demonstrated  with 
certainty  from  the  material  at  hand,  that  a  parietal  is  present  in  a  Physeter  skull  as  a 
separate  element.  Some  writers  maintain  that  it  has  fused  with  the  supraoccipital. 
This  may  be  the  true  solution  because  there  is  a  fissure,  more  distinct  in  some  places 
than  in  others,  which  separates  this  lower  temporal  process  from  the  main  body  of  the 
plate-like  supraoccipital.  By  following  this  fissure  it  becomes  evident  that  if  this 
portion  does  represent  the  parietal,  then  a  thin  plate  of  this  bone  reaches  the  vertex, 
being  inserted  between  the  supraoccipital  and  the  frontal.  On  its  external  face  this 
element  receives  an  ascending  process  of  the  squamosal  into  a  deep  triangular  fossa, 
posteriorly  it  is  in  contact  with  the  supraoccipital  above  and  the  exoccipital  below, 
and  anteriorly  the  frontal  is  deeply  mortised  into  its  anterior  margin. 

Returning  to  this  fossil  skull,  some  significance  may  attach  to  the  fact  that  a  parietal 
is  present  in  the  same  relative  position  as  in  the  young  Physeter  skull,  although  much 
larger.  Within  the  temporal  fossa,  the  sutures  bounding  the  parietal  are  well-defined 
and  there  is  also  some  evidence  for  believing  that  a  thin  plate-like  dorsal  extension  of 
this  bone  extends  at  least  part  way  to  the  vertex,  being  inserted  between  the  supra¬ 
occipital  and  frontal.  If  this  interpretation  is  correct,  then  it  corroborates  in  part 
what  appears  to  be  the  true  position  of  the  parietal  in  the  Physeter  skull  during  early 
stages  in  its  growth.  The  parietal  is  suturally  united  with  the  squamosal  posteriorly 
and  with  the  frontal  and  alisphenoid  anteriorly. 

In  this  fossil  skull,  the  alisphenoid  occupies  essentially  the  same  position  as  in 
Physeter  and  is  broadly  expanded,  extending  forward  to  the  supraorbital  process  of 
the  frontal  and  sheathing  the  posterior  borders  of  the  latter  for  a  short  distance,  and 
in  the  temporal  fossa  projects  upward,  being  bounded  on  its  upper  margin  by  the 
frontal,  posteriorly  by  the  parietal,  and  interiorly  by  the  squamosal. 


24  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


Although  the  orbit  is  small  in  the  restoration,  it  is  possible  that  it  may  have  been 
wider.  The  supraorbital  process  is  shorter  than  in  most  dolphins,  but  what  remains 
of  its  outer  margin  indicates  that  it  was  relatively  thick.  In  Physeter,  the  supraorbital 
process  is  largely  uncovered  by  the  maxilla  externally;  the  extremity  is  relatively  shal¬ 
low,  and  the  whole  structure  is  distinctly  arched.  The  postorbital  projection  extends 
farther  backward,  but  does  not  quite  come  in  contact  with  the  zygomatic  process  of 
the  squamosal.  In  Kogia,  the  postorbital  projection  overlaps  the  zygoma  for  an 
inch  or  more.  In  Physeter ,  the  lachrymal  is  wedged  in  between  the  preorbital  margin 
of  the  supraorbital  process  and  the  maxilla.  Below  the  antorbital  projection  of  the 
maxilla  and  ankylosed  to  the  lachrymal  there  is  a  narrow  curved  strip  of  bone,  the 
styliform  process  of  the  jugal,  which  forms  the  lower  boundary  of  the  orbit.  There 
is  nothing  peculiar  about  the  structure  of  the  fossil  skull  in  this  region  which  would 
suggest  a  lachyrmal  of  the  Kogia  type  (pi.  3,  fig.  1),  but  the  relations  of  the  bones 
do  favor  one  of  the  Physeter  type. 


Fig.  3. — Lateral  view  of  type  skull  of  Idiophyseter  merriami.  Cat.  No.  24287,  Palaeont.  Mus., 
Univ.  Calif.  Al.,  alisphenoid;  Ant.  n.,  antorbital  notch;  C.,  condyle;  Ex.  oc., 
exoccipital;  Fr.,  frontal;  Max.,  maxilla;  Pa.,  parietal;  Pal.,  palatine;  Pt.,  ptery¬ 
goid;  S.  oc.,  supraoccipital;  S.  or.  pr.,  supraorbital  process  of  frontal;  Sq.,  squamosal. 

The  original  outlines  of  the  zygomatic  process  can  only  be  surmised  since  the  major 
portion  of  both  processes  are  missing.  The  zygomatic  portion  of  the  squamosal  in  a 
Kogia  skull  is  drawn  out  into  a  rather  slender  process,  with  a  small  concave  fossa  for 
the  condyle  of  the  lower  jaw,  and  with  the  anterior  end  produced  downward  although 
it  does  not  meet  the  styliform  process  of  the  jugal.  In  Physeter ,  the  zygomatic  process 
is  bluntly  pointed  anteriorly,  thickened  dorso-ventrally,  and  the  upper  surface  slopes 
downward  and  forward;  the  postglenoid  process  is  scarcely  developed  as  such.  Al¬ 
though  the  major  portion  of  the  right  zygoma  is  missing,  the  surface  of  the  lower 
antero-external  corner  shows  that  this  process  must  have  been  of  moderate  size. 
Whether  or  not  the  zygoma  projected  as  far  forward  as  the  postorbital  projection  of 
the  supraorbital  plate  will  remain  a  matter  of  doubt  until  a  skull  is  found  with  these 
structures  intact. 

The  skull  as  a  whole  is  rather  heavy  and  the  slope  of  the  dorsal  and  ventral  surfaces 
imparts  a  peculiar  sub-triangular  appearance  to  the  lateral  profile.  In  front  of  the 
antorbital  notches,  the  upper  surface  of  the  maxilla  is  nearly  horizontal,  but  from  this 
point  posteriorly  it  is  deflected  upward  to  conform  with  the  peculiar  modifications 


Two  Fossil  Physeteroid  Whales.  25 

which  have  been  brought  about  in  the  frontal  during  the  development  of  the  supra- 
cranial  basin. 

The  extremity  of  the  rostrum  is  missing,  and,  as  before  indicated,  there  are  some 
grounds  for  assuming  that  it  was  relatively  shorter  than  in  Physeter.  The  lateral 
aspect  of  the  rostrum  as  far  as  preserved  is  formed  entirely  by  the  maxilla.  Between 
the  last  alveolus  and  the  antorbital  notch  the  thin  outer  margin  of  the  maxilla  has 
been  destroyed.  The  alveoli  are  visible  from  a  side  view  and  the  last  one  is  placed 
225  mm.  in  front  of  the  antorbital  notch.  This  view  best  illustrates  the  great  depth 
of  the  rostrum  in  the  region  of  the  palatines. 

Viewed  from  the  side,  the  condyles  project  beyond  the  plane  of  the  exoccipitals 
and  are  borne  on  distinct  necks.  Alterations  in  the  proportions  or  outlines  of  the 
restored  portions  -of  the  hamular  and  vaginal  processes  of  the  pterygoids  would  not 
materially  affect  the  typically  physeteroid  appearance  of  the  basicranium. 

VENTRAL  VIEW. 

The  general  contour  as  restored  (pi.  1,  fig.  2)  is  irregularly  pentagonal,  the  greatest 
width  being  across  the  zygomatic  processes.  In  this  feature,  the  restored  skull  agrees 
more  closely  with  conditions  found  in  a  skull  of  a  very  young  Physeter  catodon  (pi. 
6,  fig.  2)  than  with  a  skull  of  an  adult  Kogia  hreviceps.  In  Kogia,  the  greatest  width 
of  the  skull  is  across  the  postorbital  projections  of  the  supraorbital  processes.  Al¬ 
though  the  relations  of  the  various  elements  which  form  the  ventral  face  of  the  skull 
agree  in  some  respects  with  Kogia  and  in  others  with  Physeter ,  there  are  a  number 
of  important  differences. 

Skulls  of  Physeter  lack  functional  teeth  in  the  maxilla.  In  Kogia,  however,  there  is 
a  well-defined  alveolar  sulcus.  Authorities  differ  in  regards  Physeter,  although  all 
agree  that  the  upper  tooth  row  is  atrophied.  It  appears  that  some  skulls  do  have  as 
many  as  8  teeth  on  each  side  but  the  teeth  appear  to  be  implanted  in  the  gums.  Two 
alveoli,  however,  are  present  on  the  right  maxilla  of  this  fossil  skull  and  the  terminal 
portion  probably  contained  additional  alveoli.  Internally  each  maxilla  is  produced 
downward  to  form  a  narrow,  crest-like  ridge  which  anteriorly  gradually  merges  into 
the  convex  portion  of  the  maxilla  and  posteriorly  increases  in  width  to  agree  with  a 
corresponding  surface  of  the  palatine.  The  internal  margins  of  the  maxillae  approxi¬ 
mate  each  other  so  closely  in  front  of  the  palatines  that  only  a  slender  strip  of  the 
vomer  is  visible.  The  axial  ridge  of  the  vomer  first  appears  on  the  ventral  surface  of 
the  skull  between  the  maxillae  and  about  midway  between  the  second  alveolus  and  the 
anterior  infraorbital  foramen.  External  to  these  medial  longitudinal  crests,  the 
maxilla  is  hollowed  out,  forming  a  large  concave  area  in  front  of  the  infraorbital  fora¬ 
men.  Similar  concavities  are  present  on  the  Kogia  skull  but  are  either  ill-defined  or 
absent  on  the  young  Physeter  skull. 

On  each  side  extending  from  the  alveoli  to  the  condyles  is  a  series  of  elevations  and 
depressions  which  contribute  to  the  formation  of  the  maxillary  concavities,  orbits, 
tympano-periotic  recesses,  and  glenoid  fossae.  In  this  region  there  appear  portions 
of  the  maxilla,  lachrymal,  frontal,  palatine,  vomer  (in  part  covered  by  the  forward 
extension  of  the  pterygoid),  pterygoid,  alisphenoid,  basioccipital,  exoccipital,  and 
squamosal.  In  Kogia  there  is  but  a  single  depressed  inferior  opening  for  the  infra¬ 
orbital  system,  and  this  is  bounded  by  the  maxilla  and  lachrymal.  The  orifice  is 
situated  at  the  level  of  the  posterior  wall  of  the  nasal  passage.  On  the  ventral  surface 
of  the  maxilla  are  two  openings  for  the  infraorbital  system  in  this  fossil  skull.  The 
anterior  orifice  is  entirely  inclosed  by  the  maxilla.  The  posterior  orifice  is  bounded 
by  the  maxilla,  frontal,  and  lachrymal.  From  the  posterior  orifice  a  canal  extends 
upward  through  the  maxilla  and  opens  on  the  dorsal  face  of  the  skull  in  the  maxillary 
incisure.  The  canal  leading  upward  from  the  anterior  orifice  is  continuous  posteriorly 
with  the  previously  mentioned  canal  and  anteriorly  with  the  canal  which  passes 
through  the  substance  of  the  maxilla  above  the  tooth  row;  it  also  has  a  dorsal  orifice 


26  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast . 


in  the  maxillary  incisure.  The  wall  intervening  between  these  two  foramina  has  dis¬ 
appeared  in  the  young  Physeter  skull  and  a  single  orifice  occupies  approximately  the 
same  position  and  area  as  the  two  foramina  in  the  fossil  skull. 


Fig.  4. — Ventral  view  of  type  skull  of  Idiophyseter  merriami.  Cat.  No.  24287,  Palaeont.  Mus., 
Univ.  Calif.  Al.,  alisphenoid;  Ant.  n.,  antorbital  notch;  Ant.  inf.  f.,  anterior  in¬ 
fraorbital  foramen;  Bo.,  basioccipital;  Bs.,  basisphenoid ;  C.,  condyle;  Car.  C.,  caro¬ 
tid  canal;  Ex.  oc.,  exoccipital;  F.  ov.,  foramen  ovale;  J.  A.  C.,  jugulo-acoustic 
canal;  La.,  lachrymal;  Max.,  maxilla;  N.  A.,  nasal  passage;  Op.  c.,  optic  canal;  Pal., 
palatine;  P.  inf.  f.,  posterior  infraorbital  foramen;  Pt.,  pterygoid;  S.  or.  pr.,  supra¬ 
orbital  process  of  frontal;  Sq.,  squamosal;  Vo.,  vomer. 

Thin,  wedge-like  lachrymals,  which  are  inserted  between  the  supraorbital  plates  of 
the  frontals  and  the  maxillae,  extend  inward  beyond  the  internal  walls  of  the  orifices 
for  the  infraorbital  canals  in  the  Physeter  skull.  In  Kogia ,  the  lachrymals  are  greatly 
enlarged  and  on  the  ventral  face  of  the  skull  are  equally  if  not  more  conspicuous  than 
the  supraorbital  processes  of  the  frontals.  The  right  lachrymal  in  this  fossil  skull 
occupies  approximately  the  same  relative  position  as  in  Physeter ,  excepting  a  narrow, 
slit-like  process  which  is  not  developed  and  hence  the  lachrymal  terminates  at  the  level 
of  the  external  walls  of  the  ventral  orifices  for  the  infraorbital  system.  In  this  respect, 
the  lachrymal  of  this  fossil  skull  is  unlike  either  Kogia  or  Physeter.  The  right  lachry- 


Two  Fossil  Physeteroid  Whales. 


27 


mal  is  incomplete,  but  notwithstanding  its  position  on  the  ventral  surface,  it  was  not 
visible  from  a  dorsal  view.  The  slender  internal  process  of  the  lachrymal  which  is 
so  conspicuous  in  skulls  of  Kogia  and  Physeter  is  not  present,  and  the  most  produced 
portion  lies  between  the  two  inferior  openings  of  the  infraorbital  system.  It  does 
contribute  the  lower  boundary  of  the  antorbital  notch  as  in  Physeter.  No  primitive 
characters  are  apparent,  unless  the  intimate  relation  the  lachrymal  bears  to  the 
maxilla  and  the  supraorbital  process  of  the  frontal  be  considered  one.  Both  jugals 
are  missing.  In  the  restoration  they  are  patterned  after  those  on  the  young  Physeter 
skull. 

The  bones  of  the  palatal  region  have  suffered  some  from  erosion  and  breakage,  but 
on  the  right  side  the  palatine  is  essentially  perfect  and  the  vaginal  processes  of  the 
pterygoid  alone  are  missing.  On  the  right  side,  the  optic  canal  is  so  well  preserved 
that  the  relations  of  all  the  contributing  bones  can  be  made  out;  the  sutures  are  in¬ 
distinct  in  places,  but  can  be  traced.  The  physeteroid  characters  can  be  seen  in  the 
relations  of  the  palatines,  pterygoids,  and  vomer,  and  in  the  position  of  the  infraorbital 
openings.  In  a  Kogia  skull,  the  pterygoids  are  broadly  expanded  anteriorly,  over¬ 
spreading  the  narrow  palatines,  meeting  the  opposite  bone  along  the  median  line  of  the 
palate,  and  extending  forward  beyond  the  palatines  to  reach  the  maxilla.  The  exposure 
of  the  palatines  is  thus  reduced  to  a  small  area  represented  by  their  anterior  extremities 
which  make  their  appearance  in  front  of  the  concave  anterior  borders  of  the  pterygoids. 
On  the  other  hand,  in  a  young  Physeter  skull,  the  palatines  are  expanded  horizontally 
and  are  overridden  posteriorly  by  narrow  tongue-like  processes  of  the  pterygoids,  which 
in  some  young  skulls  project  forward  beyond  the  ventral  orifice  of  the  infraorbital 
canal.  As  near  as  can  be  determined  from  a  close  examination  of  this  fossil  skull,  the 
relations  between  the  pterygoids  and  the  palatines  appear  to  correspond  more  closely 
to  conditions  in  the  young  Physeter  skull  than  to  an  adult  Kogia  skull.  The  palatines 
of  this  fossil  skull  are  relatively  narrow,  but  they  do  not  project  forward  noticeably 
beyond  the  limits  of  the  grooves  leading  forward  from  the  anterior  infraorbital  orifices. 
'  With  the  exception  of  the  basal  portion,  the  hamular  processes  of  the  pterygoids  are 
for  the  most  part  missing.  They  appear  to  have  been  produced  backward  into  long 
processes  as  in  Physeter  and  thus  internally  form  the  floor  for  the  nasal  passages.  The 
anterior  margins  of  the  pterygoids  apparently  slide  under  the  palatines  and  thus 
contribute  the  major  portion  of  the  outer  lower  wall  of  each  nasal  passage.  In  restoring 
this  portion  of  the  fossil  skull  a  condition  approximately  halfway  between  the  Kogia 
and  Physeter  type  of  architecture  was  more  nearly  in  agreement  with  the  length  of  the 
vaginal  processes  of  the  pterygoids. 

On  the  anterior  wall  of  the  optic  canal  and  near  its  origin  there  appears  the  small 
splint-like  extremity  of  the  orbitosphenoid  which  projects  laterally  upon  the  ventral 
face  of  the  supraorbital  process  of  the  frontal.  By  making  comparisons  with  skulls  of 
Kogia  and  Physeter,  it  has  been  possible  to  work  out  most  of  the  structural  peculiarities 
of  this  region.  The  large  size  and  horizontal  expansion  of  the  alisphenoid  in  this  fossil 
skull  is  also  a  conspicuous  feature  of  the  Physeter  skull.  It  is  quadrangular  in  outline, 
bounded  anteriorly  by  the  optic  canal  and  limited  posteriorly  by  the  squamosal. 
The  large  foramen  ovale  is  directed  obliquely  through  the  alisphenoid  and  its  ectal 
orifice  lies  considerably  posterior  to  the  anterior  margin  of  the  squamosal  and  opens 
into  a  broad  groove  which  terminates  near  the  postero-external  angle  of  the  alisphenoid 
as  in  Physeter.  In  Kogia,  this  foramen  is  rather  small  and  is  situated  at  the  level  of  the 
anterior  margin  of  the  squamosal,  and  the  direction  of  the  groove  leading  from  the 
foramen  ovale  is  almost  at  right  angles  to  the  long  axis  of  the  skull.  The  optic  foramen 
is  confluent  with  the  sphenoidal  fissure  as  in  skulls  of  young  individuals  of  Kogia  and 
Physeter.  In  some  adult  skulls  of  Kogia,  a  taenia  metoptica  is  present  which  separates 
the  optic  canal  from  the  sphenoidal  fissure.  This  fissure  is  closed  ventrally  by  the 
vaginal  process  of  the  pterygoid,  anteriorly  is  limited  by  the  supraorbital  plate  of  the 
frontal,  and  is  also  bounded  posteriorly  by  the  alisphenoid.  As  in  Kogia,  the  foramen 


28  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast . 


rotundum  appears  to  be  situated  in  the  angle  formed  by  the  alisphenoid  and  frontal, 
nearest  to  the  sphenoidal  fissure. 

In  the  young  Physeter  skull,  the  canal  for  the  carotid  artery  is  rather  large  (18  mm.), 
piercing  the  alisphenoid  near  the  base  and  separated  from  the  foramen  ovale  by  an 
intervening  strip  of  bone  less  than  10  mm.  wide.  The  combined  jugulo-acoustic 
funnel  is  bordered  posteriorly  by  the  exoccipital,  internally  by  the  basioccipital,  and 
anteriorly  by  the  alisphenoid.  A  process  of  the  exoccipital  in  the  Kogia  skull  extends 
forward  to  meet  the  alisphenoid  and  bounds  this  funnel  internally,  thus  excluding  the 
basioccipital  from  its  lower  margin.  Otherwise  these  canals  are  very  similar.  In  this 
fossil  skull  the  carotid  canal  passes  through  the  alisphenoid  (text-fig.  4,  Car.  C .) 
above  the  vaginal  process  of  the  pterygoid  and  thence  through  the  substance  of  the 
falcate  process  of  the  basioccipital  for  a  total  distance  of  100  mm.  or  more  and  opens 
ectally  in  front  of  the  jugulo-acoustic  canal.  The  jugulo-acoustic  canal,  on  account  of 
a  median  constriction  appears  to  represent  two  foramina.  This  canal  lies  entirely 
within  the  exoccipital  and  pierces  this  bone  in  an  oblique  direction  for  a  distance  of  90 
mm.  The  greatest  diameter  of  the  jugulo-acoustic  foramen  at  the  point  where  it  is 
exposed  on  the  right  side  is  22  mm.;  that  for  the  carotid  canal  is  10  mm.  The  hypo¬ 
glossal  foramen  begins  internally  on  the  posterior  wall  of  the  jugulo-acoustic  funnel 
and  opens  ectally  on  the  posterior  face  of  the  exoccipital  above  the  jugular  incisure  in 
skulls  of  Kogia  and  Physeter.  It  is  present  in  the  same  position  on  the  right  exoccipital 
of  this  fossil  skull. 

The  median  region  of  the  basicranium  is  bounded  laterally  by  the  great  flanges  or 
falcate  processes  of  the  basioccipital  and  by  the  pterygoids.  It  narrows  slightly 
anteriorly  and  probably  was  partially  inclosed  by  the  hamular  processes  of  the  ptery¬ 
goids.  The  ventral  edges  of  the  vaginal  processes  of  the  pterygoid  and  the  extremities 
of  the  falcate  processes  of  the  basioccipital  are  missing.  The  general  course  and  direc¬ 
tion  of  certain  foramina  are  thus  revealed.  On  the  right  side  (text-fig.  4)  the  small 
carotid  canal  is  exposed  on  the  lateral  border  of  the  basioccipital,  some  28  mm.  posterior 
to  the  margin  of  the  vomer. 

The  basioccipital  is  a  rather  large  bone  terminated  posteriorly  by  the  paired  condyles 
and  synostosed  anteriorly  with  the  basisphenoid.  Between  the  basisphenoid  and 
basioccipital  the  medial  region  is  noticeably  swollen  transversely.  The  same  region  is 
flattened  on  skulls  of  Kogia  and  Physeter.  In  the  skull  of  the  young  Physeter,  the  sides 
of  the  basioccipital  descend  obliquely  outward  and  form  the  falcate  processes,  each  of 
which  posteriorly  abuts  against  a  similar  plate  formed  by  the  exoccipital  and  anteriorly 
limits  the  posteror  extension  of  the  corresponding  process  of  the  pterygoid.  In  the 
Kogia  skull  the  pterygoids  project  much  farther  backward  and  are  also  in  contact  with 
the  falcate  processes  of  the  basioccipital. 

In  this  fossil  skull,  the  outer  extremities  of  the  basioccipital  have  been  broken  off, 
but  nevertheless  the  relations  of  the  surrounding  bones  do  not  indicate  that  the  falcate 
processes  were  produced  any  farther  downward  than  in  Physeter.  Anterior  to  the 
occipital  condyles,  the  lower  surface  of  the  basioccipital  is  somewhat  convex,  and 
the  outer  edges  are  produced  downward  as  free  plates.  Each  of  these  falcate  processes 
forms  the  internal  boundary  for  the  corresponding  tympano-periotic  recess.  It 
appears  more  probable  that  this  region  of  the  fossil  skull  resembled  Kogia  more  closely 
than  Physeter  and  for  that  reason  the  restoration  represents  a  compromise  between  the 
two  types  of  construction.  The  suture  between  the  basioccipital  and  the  basisphenoid 
is  not  visible;  it  is  possible  that  the  basisphenoid  is  not  entirely  covered  on  its  ventral 
face  by  the  overlying  plate  of  the  vomer. 

Because  of  the  concavity  of  the  internal  borders  of  the  maxillae,  the  exposed  surface 
of  the  vomer  has  the  shape  of  a  boat  in  the  skulls  of  a  young  Physeter  and  an  adult 
Kogia.  As  remarked  before,  only  the  axial  ridge  of  the  vomer  is  visible  anteriorly  in 
this  fossil  skull  because  of  the  close  approximation  of  the  maxillae.  The  vomer  forms 
the  internal  and  posterior  wall  for  each  nasal  passage  and  extends  upward  to  meet  the 


Two  Fossil  Physeteroid  Whales. 


29 


ethmoid.  In  this  region  the  vomer  is  very  thin,  and,  following  the  deviation  of  the 
ethmoid  and  the  asymmetrical  conditions  produced  by  the  disparity  in  size  of  the  nasal 
passages,  turns  to  the  right.  At  the  point  where  these  thin  wings  of  the  vomer  are 


Measurements  of  the  skull. 


Idiophyseter 

merriami 

No.  24287, 
Univ.  Calif. 

Physeter  catodon 
(embryo) 

No.  49488, 

U.  S.  Nat.  Mus. 

Total  length  (condyles  to  tip  of  premaxillae) . 

Total  length  (as  preserved) . 

mm. 

1  735.0 

615.0 

mm. 

851. 

0 

Length  of  rostrum  (antorbital  notches  to  extremity) .  .  . 

1  388 . 0 

520. 

0 

Breadth  of  rostrum  at  antorbital  notches . 

1  368.0 

315. 

0 

Breadth  of  rostrum  at  swelling  in  front  of  antorbital 

notches . 

1  405 . 0 

347. 

0 

Greatest  breadth  of  skull  across  supraorbital  processes . . 

1  502.0 

472. 

0 

Greatest  breadth  of  skull  across  zygomatic  processes  of 

the  squamosals . 

1  555.0 

487. 

0 

Vertical  height  of  skull  (basioccipital  to  transverse  crest). 

273.0 

285 

0 

Vertical  height  of  rostrum  at  base  (level  of  antorbital 

notches) . . . 

135.0 

111 

0 

Greatest  width  of  right  maxilla  (inside  margin  to  the 

apophysis) . 

137.5 

168 

0 

Length  of  frontal  plate  of  right  maxilla  (antorbital  notch 

to  supraoccipital) . 

245.0 

250 

0 

Greatest  length  of  right  premaxilla,  as  preserved . 

490.0 

725 

0 

Greatest  breadth  of  right  premaxilla  at  level  of  nares. .  . 

105.0 

68 

0 

Greatest  breadth  of  right  premaxilla  posterior  to  nares . 

190.0 

99 

0 

Least  breadth  of  premaxilla  in  front  of  antorbital  notches 

75.0 

24 

0 

Greatest  length  of  supraorbital  process  of  right  frontal. . 

1  118.0 

97 

5 

Greatest  thickness  of  preorbital  portion  of  right  supra- 

■  r 

orbital  process . 

54.0 

18 

5 

Least  breadth  of  supraoccipital  between  temporal  fossae. 

355.0 

314 

0 

Distance  from  summit  of  transverse  crest  to  upper 

margin  of  foramen  magnum . . . 

177.5 

167 

5 

Height  of  foramen  magnum . 

73.0 

66 

0 

Breadth  of  foramen  magnum . 

71.0 

80 

0 

Greatest  breadth  across  occipital  condyles . 

216.5 

197 

0 

Greatest  vertical  diameter  of  right  condyle . 

129.0 

123 

5 

Greatest  transverse  diameter  of  right  condyle . 

78.0 

66 

2 

Distance  across  skull  between  outer  margins  of  ex- 

occipitals . 

1  540.0 

433 

0 

Distance  between  anterior  margin  of  apophysis  of  supra- 

orbital  process  of  right  frontal  and  posterior  margin 

of  right  condyle . 

425.0 

380 

.0 

Distance  across  basicranium  between  foramina  ovale. . . 

191.0 

158 

.0 

Total  length  of  vomer . . . 

470.0 

535 

.0 

Greatest  length  of  right  palatine . 

194.5 

180 

.0 

Greatest  breadth  of  right  palatine . 

60.0 

116 

.5 

Greatest  transverse  diameter  of  right  lachrymal . 

110  + 

147 

.0 

Greatest  antero-posterior  diameter  of  right  lachrymal .  . 

62.5 

61 

.8 

Greatest  antero-posterior  length  of  right  pterygoid . 

245  + 

175 

.0 

Distance  from  margin  of  foramen  magnum  to  posterior 

margin  of  vomer  along  middle  line . 

149.0 

2  191 

.0 

Greatest  breadth  of  alisphenoid  at  extremity . 

110.0 

72 

0 

Greatest  depth  of  alisphenoid  at  extremity . 

55.0 

32 

.5 

Least  distance  between  optic  canal  and  foramen  ovale. . 

60.0 

105 

0 

Least  distance  between  optic  canal  and  jugulo-acoustic 

foramen . 

135.0 

149 

.0 

Greatest  diameter  of  right  nasal  passage . 

37.0 

28 

.5 

Greatest  diameter  of  left  nasal  passage . 

60.0 

85 

.0 

1  Estimated.  2  To  anterior  margin  of  basisphenoid. 


30  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


applied  to  the  presphenoid  in  the  young  Physeter  skull  (pi.  6,  fig.  2)  they  are  broad  and 
project  laterally,  sheathing  the  anterior  face  of  the  orbitosphenoid,  touching  the  supra¬ 
orbital  process  of  the  frontal,  and  projecting  laterally  beyond  the  level  of  the  ptery¬ 
goids.  The  extremities  of  these  wings  appear  above  the  pterygoid,  bet'ween  the 
posterior  margin  of  the  palatine  and  the  optic  canal.  If  the  relations  of  the  various 
bones  surrounding  the  nasal  passages  of  this  fossil  skull  have  been  correctly  interpreted 
then  the  structural  peculiarities  are  in  entire  agreement  with  the  young  Physeter  skull. 
Furthermore,  the  extremity  of  the  lateral  wing  of  the  vomer  may  be  seen  between  the 
palatine  and  the  optic  canal  on  both  sides  in  this  fossil  skull. 

The  vomer,  which  embraces  the  presphenoid  below,  expands  horizontally  behind  the 
nasal  passages  and  sheathes  the  basisphenoid.  It  meets  the  vaginal  plates  of  the 
pterygoids  along  its  lateral  margins.  A  pair  of  narrow,  slit-like  apertures  which  expose 
the  presphenoid  appear  on  either  side  of  the  ridge  between  the  nasal  passages.  The 
posterior  margin  of  this  bone  is  concave. 

The  squamosal  bone  is  firmly  mortised  into  the  side  of  the  braincase,  extending  up¬ 
ward  to  the  dorsal  margin  of  the  temporal  fossa  as  a  narrow  wedge  bet'ween  supraocci- 
pital  and  parietal,  meeting  the  alisphenoid  anteriorly,  and  abutting  against  the  exoc- 
cipital  postero-inferiorly.  From  an  external  view,  the  squamosal  embraces  the 
alisphenoid  from  behind  in  the  temporal  fossa  and  a  long  oblique  suture  marks  their 
contact  on  the  ventral  face  of  the  skull. 

The  zygomatic  surfaces  were  not  preserved  and  until  these  parts  are  found  any  restor¬ 
ation  will  be  a  matter  of  personal  opinion.  In  Physeter,  the  fossa  for  the  reception  of 
the  condyle  of  the  mandible  is  an  ill-defined  concavity.  The  postglenoid  process  is 
short  and  round.  Anteriorly,  the  zygomatic  process  does  not  come  in  contact  with 
the  postorbital  projection  of  the  supraorbital  plate  of  the  frontal.  In  Kogia  the  post 
glenoid  process  is  hardly  discernible  and  little  more  than  a  projecting  angle  is  present 

Ontocetus  oxymycterus  Kellogg. 

Comparative  measurements  indicate  that  a  complete  skull  of  this  species  will 
measure  between  12  and  15  feet  in  length.  If  this  estimate  is  correct,  then  the  skull  of 
this  species  is  more  than  twice  as  long  as  that  of  Idiorophus  patagonicus  (Lydekker) 
from  a  lower  Miocene  tuff  formation  on  the  coast  of  Chubut  Territory,  Patagonia,  and 
probably  represents  the  largest  Miocene  physeteroid  thus  far  described.  This  speci¬ 
men1  is  tentatively  referred  to  the  genus  Ontocetus  of  Leidy. 

Type  Specimen. — Cat.  No.  10923,  Division  of  Vertebrate  Palaeontology,  United 
States  National  Museum.  The  material  includes  the  distal  end  of  the  rostrum,  the 
extremities  of  both  mandibles  with  the  roots  or  portions  of  10  or  11  teeth  in  place,  as 
well  as  several  imperfect  teeth  which  were  found  in  the  adjoining  matrix. 

Type  locality. — The  occurrence  is  as  follows:  Near  latitude  34°  20'  12"  North,  and 
longitude  119°  43'  20"  West,  in  the  sea-cliff  which  follows  the  beach  north  of  the 
Santa  Barbara  lighthouse,  Santa  Barbara  County,  California.  Range  27  West, 
Township  4  North,  Santa  Barbara  Special  Map,  U.  S.  Geological  Survey. 

Horizon. — The  specimen  was  discovered  by  Mr.  Charles  O.  Roe  about  35  years  be¬ 
fore  he  finally  removed  it  to  his  home  in  Santa  Barbara  during  the  year  1909.  The 
rostrum  and  mandibles  were  found  projecting  from  the  sea-cliff  at  an  elevation  of 
about  12  feet  above  the  high-water  mark.  The  sea-cliff  is  nearly  80  feet  high  at  the 
point  where  the  skull  was  found,  but  the  writer  can  not  give  any  estimate  as  to  the 
thickness  of  the  stratum  or  as  to  the  relative  position  of  the  specimen  within  it.  I  am 
indebted  to  Mr.  Earl  V.  Shannon,  Assistant  Curator  of  Geology,  for  the  following  report 
on  the  matrix: 

"The  specimen  submitted  for  examination  consists  of  a  dense,  almost  aphanitic 
laminated  rock  of  medium  olive-buff  color.  Superficially  it  resembles  a  rhyolite 

1  R.  Kellogg,  A  fossil  physeteroid  cetacean  from  Santa  Barbara  County,  California,  Proc . 
U.  S.  Nat.  Mus.,  vol.  66,  Publ.  2564,  pp.  1-8,  pis.  1,  2,  1925. 


Two  Fossil  Physeteroid  Whales. 


31 


with  flow  structure  more  than  a  sedimentary  rock  and  this  resemblance  is  heightened 
by  scattered  nearly  spherical  cavities  a  millimeter  or  two  in  diameter,  which,  under  a 
binocular  microscope,  are  seen  to  be  lined  with  minute,  sparkling,  rhombohedral, 
colorless,  or  slightly  yellowish  crystals.  In  1  :  1  hydrochloric  acid  the  rock  effervesces 
slowly  in  the  manner  characteristic  of  a  dolomite  and  upon  warming  in  the  acid  large 
pieces  are  completely  dissolved,  leaving  little  residue  and  with  the  separation  of  a  con¬ 
siderable  amount  of  oily  matter.  The  solution,  after  removal  of  iron,  lime,  etc.,  in 
the  usual  manner,  reacts  copiously  for  magnesia  with  microcosmic  salt.  The  rock 
is  evidently  a  fairly  pure  bituminous  dolomite.” 

No  direct  reference  to  the  strata  which  comprise  the  sea-cliff  west  of  the  Santa  Bar¬ 
bara  lighthouse  can  be  found  and  Arnold1  states  that  “the  structure  of  the  coast 
west  of  Punta  del  Castillo  was  not  studied.”  This  stratum  of  bituminous  dolomite, 
however,  probably  represents  one  of  the  calcareous  deposits  which  alternated  with 
siliceous  deposits  to  form  the  thick  series  known  as  the  lower  division  of  the  Monterey 
formation.  In  the  report  by  Arnold  and  Anderson,2  reference  is  made  to  “massive 
beds  of  peculiar  sand-colored  limestone  with  characteristic  lamellar  weathering.” 
Again  in  referring  to  a  bituminous  limestone  [a  bituminous  dolomite  as  shown  by  No. 
11  in  the  table  of  analyses,  op.  cit.,  p.  45]  from  Redrock  Mountain,3  northeast  of  Lom¬ 
poc,  Santa  Barbara  County,  they  report  as  follows:  “The  last  analysis  (No.  11) 
represents  a  limestone  typical  in  lithologic  appearance  of  the  limestone  of  the  Mon¬ 
terey.”  The  age  of  this  formation  is  Middle  Miocene,  Helvetian,  or  later. 

Rostrum. 

As  the  base  of  the  rostrum  and  the  braincase  still  remain  in  the  sea-cliff  near  Santa 
Barbara,  an  exact  idea  of  this  physeteroid’s  relation  to  previously  described  skulls 
can  not  be  given  at  present.  The  general  outlines  of  the  skull,  however,  were  probably 
similar  to  Idiorophus  and  Scaldicetus.  According  to  the  figures  of  Scaldicetus  morteze- 
lensis  given  by  Abel,4  the  extremity  of  the  rostrum  of  that  species  is  not  characterized 
by  a  lateral  compression.  This  is  the  most  apparent  difference  between  the  rostrum 
of  the  Santa  Barbara  cetacean  (pi.  7,  fig.  1)  and  that  of  Scaldicetus.  The  size  of  the 
teeth  and  the  general  appearance  of  their  dentinal  axes  indicate  some  relationship 
with  Ontocetus.  With  the  possible  exception  of  Idiophyseter  merriami,  all  previously 
described  skulls  of  fossil  physeteroids,  in  so  far  as  can  be  judged  from  the  imperfectly 
preserved  specimens  now  known,  were  characterized  in  part  by  the  presence  of  3  teeth 
in  the  extremity  of  each  premaxilla.  In  these  forms  the  extremity  of  the  rostrum  is 
formed  by  the  premaxillae  alone.  In  this  Santa  Barbara  skull  (pi.  7,  fig.  2),  also,  the 
premaxillae  take  part  in  the  formation  of  the  extremity  of  the  rostrum  and  3  of  the 
teeth  on  each  side  are  implanted  in  the  premaxilla.  The  lateral  compression  of  the 
distal  portion  of  the  rostrum  is  quite  noticeable  in  certain  genera,  particularly  so  in 
Idiorophus  patagonicus  and  Orycterocetus  mediatlanticus.  The  extremity  of  the  ros¬ 
trum  of  this  fossil  physeteroid  was  constricted  from  side  to  side  and  the  inner  margins 
of  the  premaxillae  are  in  contact  along  the  median  line  as  in  Idiorophus  patagonicus, 
forming  a  roof  for  the  mesorostral  gutter.  On  comparing  the  dorsal  view  of  this  Santa 
Barbara  rostrum  with  that  of  Physeter ,5  other  peculiarities  become  apparent.  In 
the  latter,  the  rostrum  is  more  or  less  attenuated  anteriorly,  but  the  abrupt  constric¬ 
tion  or  lateral  compression  of  the  distal  portion  of  the  rostrum  has  disappeared  with 
the  horizontal  expansion  of  the  rostrum  as  a  whole. 

1  R.  Arnold,  Geology  and  oil  resources  of  the  Summerland  District,  Santa  Barbara  County, 
California,  Bull.  No.  321,  U.  S.  Geol.  Surv.,  p.  38,  1907. 

2  R.  Arnold  and  R.  Anderson,  Geology  and  oil  resources  of  the  Santa  Maria  Oil  District, 
Santa  Barbara  County,  California,  Bull.  No.  322,  U.  S.  Geol.  Surv.,  p.  34,  1907. 

3  R.  Arnold  and  R.  Anderson,  op.  cit.,  p.  44. 

4  O.  Abel,  Mem.  Mus.  roy.  d’hist.  nat.  de  Belgique,  Bruxelles,  tome  3,  p.  67,  text  fig.  5,  1905. 

5  P.  J.  Van  Beneden  and  P.  Gervais,  Ost6ographie  des  Cetaces  vivants  et  fossiles,  Atlas,  pi. 
19,  figs.  5,  6,  1880. 


32  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


While  removing  the  matrix,  it  became  evident  that  this  skull  had  partially  decayed 
before  it  was  completely  buried  in  the  sediments  which  preserved  it.  Furthermore, 
some  of  the  teeth  were  broken  off  in  the  alveoli  previous  to  its  burial,  for  on  removing 
the  matrix  which  covered  the  right  mandible  (pi.  8,  fig.  2),  the  roots  of  the  teeth  were 
exposed  to  view.  Other  teeth  dropped  out  of  the  alveoli  in  the  upper  jaws  after  the 
skull  was  covered  with  sediments  as  several  were  found  in  the  matrix.  The  outer 
surfaces  of  the  maxilla  are  worn,  more  in  some  places  than  in  others.  Nevertheless, 
it  appears  that  the  anterior  alveoli  in  the  maxilla  are  separated  from  the  outer  surface 
by  a  very  thin  plate,  hardly  more  than  15  mm.  in  thickness.  The  lateral  border  of 
the  maxilla  overhangs  the  alveoli  more  noticeably  posteriorly  than  anteriorly.  The 
alveoli  in  the  maxillae  agree  in  size  with  those  for  the  corresponding  teeth  in  the 
mandibles.  At  least  8  alveoli  are  present  in  the  distal  end  of  each  maxilla  and  a  com¬ 
plete  skull  may  have  carried  18  or  more  teeth  in  each  jaw.  From  the  inferior  margin, 
the  maxilla  (pi.  8,  fig.  2)  curves  upward  to  the  premaxilla  in  a  gradual  curve  which 
becomes  more  pronounced  as  the  maxilla  attains  a  greater  depth  posteriorly.  Appar¬ 
ently,  the  horizontal,  plate-like,  inwardly  projecting  portions  of  the  premaxillae  do  not 
roof  the  mesorostral  gutter  to  the  extremity  of  the  rostrum,  but  this  can  not  be  stated 
with  any  degree  of  certainty,  for  although  they  taper  rapidly  their  extremities  are 
clearly  mutilated.  The  maxillae  gradually  increase  in  breadth  toward  the  base  of 
this  section  of  the  rostrum  and  then  appear  to  suddenly  expand  as  would  be  expected 
in  a  skull  characterized  by  a  lateral  compression  of  the  extremity  of  the  rostrum. 
From  a  lateral  view  the  maxillae  increase  in  depth  as  they  approach  the  base,  whereas 
the  premaxillae  decrease. 

The  mesorostral  gutter  extends  the  full  length  of  the  rostrum.  Its  distal  extension 
is  made  up  entirely  by  the  premaxillae  which  meet  mesially  on  the  floor  in  a  linear 
suture.  Posterior  to  the  third  pair  of  alveoli  is  the  distal  extremity  of  the  vomer 
which  contributed  the  floor  of  the  gutter  for  most  of  its  length,  and  on  each  side  is 
mortised  into  the  ventral  extensions  of  the  premaxillae,  and  they  in  turn  are  applied 
to  the  inner  borders  of  the  maxillae.  From  its  extremity  posteriorly,  the  vomer 
increases  in  width  and  eventually  gains  a  position  on  the  walls.  The  dorsal  wall  or 
roof  of  the  vomerine  gutter  is  formed,  as  mentioned  above,  by  the  overhanging  plate¬ 
like  portions  of  the  premaxillae.  From  the  level  of  the  third  pair  of  alveoli  posteriorly, 
the  premaxillae  retain  a  nearly  uniform  breadth. 

Mandibles. 

Since  this  specimen  projected  from  the  face  of  the  cliff  and  was  exposed  to  the  action 
of  the  elements  for  35  years  at  least,  it  is  not  surprising  that  the  inferior  surfaces  of 
the  mandibles  should  exhibit  evidence  of  considerable  erosion.  From  a  ventral  view 
(pi.  8,  fig.  1),  numerous  branching  canals  are  now  visible,  although  they  are  filled  with 
matrix,  which  afforded  passage  for  nerves  and  blood-vessels.  In  places,  this  wear  has 
amounted  to  an  inch  or  more  in  thickness.  The  extremities  of  the  mandibles  are  rela¬ 
tively  large  in  comparison  to  the  rostrum  and  in  general  conformation  are  somewhat 
similar  to  those  of  Physeter.  Pressure  or  other  factors  resulted  in  the  separation  of 
the  mandibles  at  the  symphysis.  The  left  mandible  does  not  lie  in  its  normal  position 
and  its  inner  face  is  appressed  against  the  ventral  surface  of  the  rostrum.  The  proxi¬ 
mal  portions  of  the  mandibles  were  not  collected  and,  as  the  inner  faces  of  distal  sec¬ 
tions  commence  to  diverge  some  170  mm.  in  front  of  the  point  where  they  were  broken 
off,  it  is  evident  that  all  of  the  symphysial  region  is  represented;  if  this  is  the  case,  then 
the  symphysis  of  the  mandible  is  co-extensive  with  the  first  8  pairs  of  teeth.  Both 
mandibles  curved  upward  from  the  posterior  end  of  the  symphysis  forward.  The  distal 
extremity  of  each  mandible  is  obliquely  truncated  in  a  dorso-ventral  direction,  while 
the  external  and  internal  faces  of  the  mandible  descend  abruptly  from  the  dorsal  surface 
which  is  relatively  flat. 

The  tooth-bearing  portion  of  the  mandible  is  relatively  massive  and  the  bone  itself  is 
rather  dense.  The  alveoli  (pi.  8,  fig.  2)  are  large  and  the  posterior  ones  occupy  more 
than  half  of  the  width  of  the  mandible.  In  this  fossil,  the  series  of  teeth  in  each 


Two  Fossil  Physeteroid  Whales . 


33 


mandible  consists  of  more  than  11  slightly  curved  and  conical  teeth.  The  first  and 
third  teeth  are  the  smallest  of  the  mandibular  series.  The  roots  of  all  the  teeth  avail-, 
able  for  examination  from  the  upper  jaw  are  terminated  obtusely  and  no  doubt  those 
of  the  mandible  are  similar  in  appearance.  Two  teeth,  the  inner  one  much  smaller 
than  all  of  the  following  with  the  exception  of  the  third,  project  obliquely  forward  from 
the  extremity  of  each  mandible. 

Teeth. 

Turning  to  the  teeth,  we  find  that  they  are  all  very  large  and  that  some  may  have  pro¬ 
jected  4  or  5  inches  beyond  the  jaws.  They  are  separated  by  intervals  or  septa  nar¬ 
rower  than  the  thickness  of  the  cement.  In  respect  to  their  mode  of  implantation  in 
the  jaw,  the  teeth  differ  from  those  of  Physeter  in  that  they  are  lodged  in  distinct 
alveoli  and  the  septa  extend  the  full  depth  of  the  alveolus.  These  alveoli  are  too 
large  to  hold  the  teeth  in  place  independently  of  a  dense  ligamentous  gum  which  ac¬ 
counts  for  their  absence  from  the  alveoli  in  the  upper  jaw.  The  position  of  the  man¬ 
dibles  prevented  the  teeth  from  falling  out  of  the  alveoli  and  in  some  instances  the 
matrix  in  the  alveolus  which  encircles  the  root  attains  a  width  of  20  mm.  or  more. 
This  interval  affords  another  indication  of  how  loosely  the  teeth  were  implanted  in  the 
jaws.  All  the  crowns  of  the  teeth,  with  the  exception  of  the  third  in  the  right  mandible, 
either  were  broken  off  at  the  time  the  specimen  was  removed  from  the  sea-cliff  or  were 
destroyed  before  burial.  The  summit  of  the  crown  of  this  tooth  is  abraded  or  broken 
and  the  enamel  is  ornamented  with  coarse  longitudinal  striae. 

The  crown  of  the  third  mandibular  tooth  is  broken  off  obliquely  in  an  interno- 
external  direction.  The  enamel  forms  a  band  encircling  the  crown  of  the  tooth,  about 
1  mm.  in  thickness  and  approximately  35  mm.  in  depth  when  complete.  The  crown 
and  upper  part  of  a  tooth,  which  broke  away  from  the  end  of  the  root  in  the  mandible  at 
the  time  the  specimen  was  removed  from  the  sea-cliff,  measures  153  mm.  in  length. 
The  greatest  transverse  diameter  of  the  base  of  this  apical  section  of  the  tooth  equals 
78  mm.  and  the  maximum  thickness  of  the  cement  is  9.5  mm.  At  the  level  of  the 
superior  face  of  the  mandible,  the  outer  coat  of  cement  of  these  teeth  varies  from  10 
to  19  mm.  in  thickness.  From  these  measurements  it  is  evident  that  a  short  section 
of  the  tooth  which  intervenes  between  this  apical  portion  and  the  distal  extremity  or 
root  is  missing.  A  large  mandibular  tooth  will  measure  at  least  300  mm.  in  length. 
The  roots  of  these  teeth  are  fusiform,  remarkably  robust,  and  very  large  in  proportion 
to  the  crown.  They  are  almost  straight  at  the  basal  two-thirds,  but  curved  toward 
the  crown  so  that  the  latter  appears  to  be  obliquely  placed  upon  it.  The  enamel  on 
the  crown  does  not  form  an  enlargement  at  the  base  and  passes  into  the  cement  on 
the  root  without  any  perceptible  increase  or  decrease  in  the  diameter  of  the  neck- 
hence  there  is  no  distinct  neck  and  no  constriction  at  this  point  can  be  observed  on  any 
of  the  teeth  which  are  sufficiently  preserved  to  offer  any  data.  The  distal  extremities 
of  all  the  teeth  are  present  in  the  left  mandible.  At  the  point  where  they  are  broken 
off,  a  small  pulp  cavity  is  exposed  in  the  second  and  ninth  teeth,  measuring  3.5  and  7.5 
mm.  respectively  in  diameter.  This  indicates  that  the  lower  portions  of  the  roots  were 
pervaded  by  a  slender  pulp  cavity,  irregular  in  diameter  because  of  the  presence  of 
nodosities  on  the  sides. 

As  seen  in  cross-section,  the  teeth  consist  of  an  internal  cone  of  ossified  pulp  and 
dentine  which  is  covered  externally  by  a  thick  layer  of  cement.  This  outer  coat  of 
cement  is  usually  brownish  in  contrast  to  the  light  cream-colored  dentine,  and  on  the 
eighth  tooth  of  the  right  mandible  is  equal  to  about  one-fourth  of  the  transverse  diam¬ 
eter  of  the  root.  The  dentinal  axis  is  formed  in  concentric  layers  while  the  cement  on 
the  other  hand  appears  to  be  composed  of  thin  and  narrow  longitudinal  strips  or  lamina. 
In  cross-section,  the  ends  of  these  lamina  are  so  arranged  that  their  axes  correspond 
to  lines  radiating  from  the  center  of  the  pulp  cavity. 

The  most  obvious  distinction  between  these  teeth  and  that  of  Ontocetus  emmonsi  is 
the  relative  thickness  of  the  outer  layer  of  cement.  In  cross-section  the  central  axis 
of  dentine  appears  to  be  more  or  less  ovoidal  in  the  anterior  mandibular  teeth  in  con- 


34  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


trast  to  the  circular  outlines  of  the  posterior  ones,  but  this  may  be  due  in  part  to  differ¬ 
ences  in  the  direction  of  the  teeth  in  the  alveoli,  the  former  being  implanted  more 
obliquely  than  the  latter.  Thin  ridges  which  encircle  the  dentinal  axis  and  which 
have  been  referred  to  as  annular  lines  of  growth  are  present.  Longitudinal  grooves  or 
fluting,  varying  in  number  and  in  depth  among  the  several  teeth  at  hand,  further  char¬ 
acterize  the  external  surface  of  the  dentinal  axis.  The  teeth  of  Scaldicetus  caretti,  a 
physeteroid  whale  from  the  Anversian  of  Belgium,  agree  with  those  of  this  Californian 
species  in  size. 

All  of  the  teeth  are  imperfectly  fossilized  and  the  dentine  especially  is  rather  soft 
and  pithy.  In  their  present  state,  difficulties  which  are  familiar  to  anyone  who  has 
attempted  to  preserve  tusks  of  mastodons,  are  encountered  when  the  teeth  are  freed 
from  the  matrix.  The  teeth  fracture  and  crumble  even  when  every  precaution  is 
taken  for  their  preservation. 


Measurements  on  the  rostrum  and  mandibles. 

mm. 

Total  length  of  rostral  section  along  the  median  line .  845 

Width  of  right  premaxilla  at  proximal  end  of  rostral  section .  97 

Width  of  right  premaxilla  at  level  of  second  alveolus .  91 

Depth  of  right  premaxilla  at  proximal  end  of  rostral  section .  190 

Depth  of  right  premaxilla  above  maxillary  suture  at  level  of  fifth  alveolus .  69 

Breadth  of  rostral  section  at  proximal  end  (left  maxillary  surface  worn) .  405 

Breadth  of  rostral  section  at  point  100  mm.  posterior  to  distal  end .  170 

Breadth  across  combined  premaxillae  at  proximal  end  of  rostral  section .  213 

Breadth  across  combined  premaxillae  at  level  of  fifth  alveolus .  211 

Total  length  of  section  of  right  mandible .  965 

Depth  of  right  mandible  at  proximal  end  of  section .  192 

Depth  of  right  mandible  at  extremity .  117 

Breadth  of  right  mandible  at  proximal  end  of  section .  175 

Breadth  of  right  mandible  at  extremity .  123 

Total  length  of  section  of  left  mandible .  920 

Depth  of  left  mandible  at  proximal  end  of  section .  196 

Depth  of  left  mandible  at  extremity .  115 

Breadth  of  left  mandible  at  proximal  end  of  section .  180 

Breadth  of  left  mandible  at  extremity .  117 

Greatest  transverse  diameter  of  root  of  first  tooth,  left  mandible .  54 

Greatest  transverse  diameter  of  root  of  second  tooth,  left  mandible .  74 

Greatest  transverse  diameter  of  root  of  third  tooth,  left  mandible .  70 

Greatest  transverse  diameter  of  root  of  fourth  tooth,  left  mandible .  66.5 

Greatest  transverse  diameter  of  root  of  fifth  tooth,  left  mandible .  67.5 

Greatest  transverse  diameter  of  root  of  sixth  tooth,  left  mandible .  70 

Greatest  transverse  diameter  of  root  of  seventh  tooth,  left  mandible .  78.5 

Greatest  transverse  diameter  of  root  of  eighth  tooth,  left  mandible .  89 

Greatest  transverse  diameter  of  root  of  ninth  tooth,  left  mandible .  90.5 

Greatest  transverse  diameter  of  root  of  tenth  tooth,  left  mandible .  71 

Length  of  enamel  crown  of  third  tooth,  right  mandible  (apex  missing  or  abraded) .  30-j- 

Greatest  antero-posterior  diameter  of  enamel  crown  of  third  tooth  at  base,  right  mandible  32 
Eighth  tooth,  right  mandible. 

Transverse  diameter  of  tooth  at  level  of  superior  face  of  mandible .  82 

Transverse  diameter  of  dentinal  axis .  50 

Greatest  width  of  cement  in  same  plane .  18 

Pulp  cavity  closed. 

Eighth  tooth,  left  mandible. 

Transverse  diameter  of  tooth  at  level  of  superior  face  of  mandible .  93 

Transverse  diameter  of  dentinal  axis .  62 

Greatest  width  of  cement  in  same  plane .  19 

Pulp  cavity  closed. 

Ninth  tooth,  right  mandible. 

Transverse  diameter  of  tooth  at  level  of  superior  face  of  mandible .  80 

Transverse  diameter  of  dentinal  axis .  46.3 

Greatest  width  of  cement  in  same  plane .  19 

Transverse  diameter  of  pulp  cavity  at  same  plane .  7.5 


II.  FOSSIL  CETOTHERES  FROM  CALIFORNIA. 


Since  Edward  D.  Cope  published,  in  1872,  the  description  of  the 
mandible  of  Eschrichitus  davidsonii,  several  specimens  from  Miocene 
formations  on  the  Pacific  Coast  of  North  America  belonging  to  the 
group  of  cetaceans  known  as  whalebone  whales  have  found  their  way 
into  collections.  Some  of  these  specimens  furnish  considerable 
additional  information  regarding  the  structural  peculiarities  of  the 
skull  and  skeleton.  The  material  discussed  in  the  present  paper 
includes  three  skulls,  one  of  which  was  associated  with  a  nearly 
complete  skeleton.  All  of  the  skulls  are  more  or  less  distorted  from 
crushing,  with  different  elements  missing  at  the  time  of  collection 
or  misplaced  during  the  long  interval  which  has  elapsed  since  their 
discovery.  They  also  differ  in  size;  the  one  preserved  in  the  block  of 
matrix  in  association  with  vertebrae  and  ribs  is  the  largest ;  the  other 
two  are  of  approximately  the  same  size  and  appear  to  be  conspecific, 
notwithstanding  certain  minor  differences  in  the  illustrations. 

Many  hours  have  been  spent  in  an  endeavor  to  reach  an  under¬ 
standing  of  the  relations  of  these  specimens  to  previously  described 
cetotheres.  The  types  of  practically  all  of  the  North  American  Ter¬ 
tiary  forms  have  been  examined  and  actually  compared  with  these 
specimens.  Thirty-five  genera  of  Tertiary  mysticetes  have  been 
proposed,  but  not  all  of  these  are  valid.  A  careful  perusal  of  the 
literature  will  convince  anyone  that  the  generic  allocations  of  many 
of  the  described  species  are  inconsistent  with  the  structural  peculi¬ 
arities  of  the  skulls.  A  discussion  of  these  species  would  entail  a 
general  revision  of  the  whole  group,  but  this  is  beyond  the  scope  of 
the  present  paper.  It  seems,  therefore,  proper  that  all  comparisons 
should  be  limited  to  those  forms  which  obviously  have  some  bearing 
on  the  relationships  of  these  California  cetotheres. 

Various  writers  have  discussed  these  Miocene  cetotheres,  but  each 
writer  appears  to  have  a  somewhat  different  conception  of  their 
relationships.  Attempts  have  been  made  to  base  generic  distinctions 
upon  different  features  in  cranial  architecture.  It  was  Cope1  who 
classified  the  cetotheres  upon  the  mandibles,  True2  on  differences  in 
the  slope  of  the  supraorbital  plate  of  the  frontal  and  the  relations  of 
the  parietal  bones  to  the  adjoining  elements,  Winge3  on  the  position 

1  E.  D.  Cope,  Fourth  contribution  to  the  marine  fauna  of  the  Miocene  Period  of  the  United 
States,  Proc.  Amer.  Philos.  Soc.,  Philadelphia,  vol.  34,  No.  147,  pp.  139-154,  pi.  6,  May  29,  1895. 

2  F.  W.  True,  The  genera  of  fossil  whalebone  whales  allied  to  Balaenoptera,  Smithson.  Misc. 
Coll.,  vol.  59,  No.  6,  Publ.  2081,  pp.  1-8,  April  3,  1912. 

*  H.  Winge,  Udsigt  over  Hvalernes  indbyrdes  Slaegtskab.  Vidensk.  Medd.  fra  Dansk,  naturh. 
Foren.,  Kjpbenhavn,  Bd.  70,  pp.  73-80,  1918;  A  review  of  the  interrelationships  of  the  Cetacea, 
Smithson.  Misc.  Coll.,  vol.  72,  No.  8,  Publ.  2650,  pp.  16-22.  1921. 

35 


36  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


and  extent  of  the  glenoid  articular  surface  for  the  condyle  of  the 
lower  jaw,  but  Van  Beneden1  was  the  first  to  point  out  the  import¬ 
ance  of  the  ear  bones  for  purposes  of  classification,  although  in  later 
years  he  attributed  considerable  importance  to  the  position  and 
relations  of  the  condyle  of  the  mandible. 

In  only  one  of  these  skulls  from  California  is  there  anything  of 
the  rostrum  preserved.  This  skull  also  shows  the  proportions  and 
shape  of  the  supraorbital  processes  of  the  frontals.  Nevertheless,  the 
degree  of  forward  thrust  of  the  supraoccipital  shield  and  the  back¬ 
ward  thrust  of  the  mesial  portion  of  the  rostrum,  the  unusually 
slender  supraorbital  processes,  the  position  of  the  nasals,  as  well  as 
the  relations  of  the  bones  in  the  intertemporal  region  are  so  definitely 
like  Cetotherium  rathkii,  that  there  appears  to  be  little  doubt  but  that 
this  specimen  should  be  allocated  to  that  genus.  The  other  skulls, 
in  so  far  as  can  be  determined  by  comparisons  with  figured  specimens 
and  descriptions,  appear  to  be  referable  to  the  genus  Plesiocetus. 
In  this  genus,  however,  the  relations  between  the  rostrum  and  the 
cranium  are  not  fully  known.  Another  genus,  Mesocetus ,  should  be 
mentioned  in  this  connection,  because  of  the  confusion  which  still 
exists  as  to  the  structural  peculiarities  of  the  skull  which  distinguish 
this  genus  from  Plesiocetus.  According  to  the  illustrations  given  by 
Van  Beneden,  the  degree  of  interdigitation  between  the  rostral  and 
cranial  portions  of  the  skull  in  species  of  the  genus  Mesocetus  repre¬ 
sents  an  advanced  stage  in  the  general  trend  toward  telescoping. 
The  periotics  of  the  species  from  the  Antwerp  Basin,  Belgium, 
referred  to  Mesocetus ,  as  compared  to  that  of  Plesiocetus  hupschii, 
present  features  which  may  indicate  a  generic  difference. 

One  gathers  the  impression  that  the  skulls  of  the  species  referable 
to  the  Miocene  genus  Cetotherium  were  characterized  by  curved 
supraorbital  processes,  by  the  facial  position  of  the  nasals,  by  long, 
slender,  zygomatic  processes  with  peculiar,  elongated,  glenoid 
articular  surfaces,  as  well  as  by  long,  slender  mandibles,  a  conception 
that  is  strengthened  by  a  comparison  of  the  various  described  species. 
The  backward  thrust  of  the  mesial  portion  of  the  rostrum  has  carried 
the  ascending  processes  of  the  maxillae  and  premaxillae,  as  well  as 
the  nasals,  beyond  the  level  of  the  preorbital  angles  of  the  supra¬ 
orbital  processes.  In  consequence  of  this  backward  movement,  the 
facial  portion  of  the  skull  is  dished  in  mesially,  the  anterior  borders 
of  the  supraorbital  processes  curving  forward  and  outward.  These 
supraorbital  processes  slope  gradually  outward  from  the  dorsal 
surface  of  the  interorbital  region  and  are  never  abruptly  depressed 

1  P.  J.  Van  Beneden,  Observations  sur  les  caracteres  sp6cifiques  des  grands  cetac6s,  tires  de  la 
conformation  de  l’oreille  osseuse,  Ann.  Sci.  Nat.,  Paris,  ser.  2,  tome  6,  Zoologie,  pp.  158-159, 
1836;  Description  des  ossements  fossiles  des  environs  d’Anvers,  Ann.  Mus.  Roy.  d’Hist.  Nat. 
de  Belgique,  Bruxelles,  C6tac6s,  tome  4,  pp.  1-83,  1880,  pis.  1-39,  1878;  op.  cit.,  tome  7,  pp.  1-90, 
pis.  40-109,  1882;  op.  cit.,  tome  9,  pp.  1-40,  pis.  1-30,  1885;  op.  cit.,  tome  13,  pp.  1-139,  pis.  1-75, 
1886, 


Fossil  Cetotheres. 


37 


below  the  level  of  the  latter  as  in  the  living  balaenopterine  whales. 
Cetotherium  appears  to  be  the  only  Miocene  mysticetacean  in 
which  the  supraorbital  processes  are  slender  and  noticeably  narrower 
at  the  base  than  at  the  extremity.  If  we  take  the  features  seriatum, 
we  find  first  of  all  that  the  skulls  of  these  cetotheres  retained  a  well- 
defined  intertemporal  region  which  was  constituted  entirely  by  the 
parietals  which  meet  mesially  along  the  median  line  in  front  of  the 
supraoccipital  shield.  In  most  species,  the  braincase  is  short  and 
broad,  and  the  apex  of  the  supraoccipital  shield  lies  behind  the  level 
of  the  orbit.  So  far  as  known,  the  rostrum  is  never  laterally  com¬ 
pressed.  The  ascending  process  of  the  maxilla  is  narrow  and  is 
suturally  united  with  the  frontal.  It  does  not  overspread  the  supra¬ 
orbital  process  of  the  frontal.  The  general  arrangement  of  the  bones 
which  form  the  nasal  passages  is  more  nearly  in  agreement  with  the 
typical  structure  of  terrestrial  mammals  than  with  the  toothed  whales. 
The  nasals  and  mesial  projections  of  the  frontals  completely  roof 
over  the  ethmoid  region,  and  in  addition  the  palatine  is  excluded 
from  the  anterior  wall  of  the  corresponding  nasal  passage.  The 
choanae  lie  behind  the  anterior  narial  apertures  and  the  orbital  plate 
of  the  maxilla  is  retained. 

During  the  early  stages  in  the  development  of  the  embryonic 
whalebone  whale  skull,  teeth  are  present  in  each  jaw,  but  they  are 
absorbed  long  before  the  birth  of  the  animal.  The  evidence  afforded 
by  embryological  studies  suggests  toothed  ancestors  for  the  Mysti- 
ceti,  although  it  does  not  show  what  type  of  cetacean  may  have 
been  ancestral.  The  Upper  Eocene  and  Oligocene  toothed  whales, 
especially  Patriocelus,  were  held  by  Abel1  to  be  the  predecessors  of 
the  living  whalebone  whales.  This  derivation  has  been  questioned  by 
Miller2  and  he  calls  attention  to  the  restoration  given  by  Abel  for 
Patriocelus  in  which  the  premaxilla  is  shown  extending  backward 
to  the  parietal  and  the  maxilla  terminating  in  front  of  the  orbit. 
Furthermore,  one  of  the  characteristic  features  of  the  Mysticeti, 
the  orbital  plate  of  the  maxilla,  appears  to  be  missing  on  the  Patrio - 
cetus  skull.  At  any  event,  the  specimens  now  known  do  not  support 
the  derivation  of  the  cetotheres  from  the  archaic  toothed  whales 
grouped  under  the  family  Agorophiidae. 

The  undiscovered  predecessors  of  the  cetotheres  may  some  day  be 
found  in  Eocene  formations;  at  least  by  the  close  of  the  Upper 
Oligocene,  the  cetotheres  were  already  well  established.  In  case  of 
the  mysticetes,  the  interdigitation  of  the  rostral  and  cranial  por¬ 
tions  of  the  skull,  in  so  far  as  substantiated  by  described  speci¬ 
mens,  is  observed  only  in  genera  which  make  their  appearance  after 

1  O.  Abel,  Die  Vorfahren  der  Bartenwale,  Denkschr.  Kais.  Akad.  Wiss.  math.-naturw.  Ed., 
Wien,  Bd.  90,  pp.  28-34,  57-68,  pis.  1-4,  6,  11,  12,  1913. 

2  G.  S.  Miller  jr.,  The  telescoping  of  the  cetacean  skull,  Smithson.  Miac.  Coll.,  vol.  76,  No.  5, 
Publ.  2720,  pp.  23,  42-44,  1923. 


38  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


the  close  of  the  Burdigalian  stage.  These  early  cetotheres  had  lost 
their  teeth  and  acquired  two  rows  of  bladelike  plates  of  baleen 
depending  from  the  roof  of  the  mouth  which  served  as  a  sieve  when 
the  animal  was  feeding.  Small  crustaceans  or  fish  constitute  the 
food  of  the  living  whalebone  whales  and  the  cetotheres  no  doubt 
subsisted  on  the  same  types  of  food.  In  the  case  of  the  living  balaen- 
opterine  whales,  numbers  of  small  fish  are  engulfed  in  the  oral 
cavity  when  feeding,  along  with  a  large  quantity  of  water  which 
necessarily  must  be  expelled  before  such  small  prey  can  be  swallowed. 
Hence  these  plates  of  baleen  with  internal  marginal  fringes  of 
intermatted  bristle-like  fibers  form  a  strainer  remarkably  well 
adapted  for  taking  surface  swimming  crustaceans  or  for  impounding 
the  small  fish  which  are  scooped  up  when  the  cetacean  plunges 
through  a  shoal  with  an  open  mouth.  It  is  well  known  that  herrings, 
anchovies,  and  the  like  are  often  found  in  exceedingly  large  shoals 
in  the  seas  at  the  present  time.  Small  fish  abounded  in  the  waters 
along  the  coast  of  southern  California  during  Monterey  time,  as  is 
evidenced  by  the  presence  of  a  small  herring-like  fish  (Xyne  grex )  in 
the  diatomaceous  shales  at  Lompoc,  California,  in  such  enormous 
numbers  that  their  remains  at  one  level  in  this  horizon  are  spread 
like  a  blanket  over  an  area  which  can  only  be  estimated  by  acres.  But 
as  Jordan1  states,  these  small  delicate  fish  were  inhabitants  of  shallow 
bays,  and  inasmuch  as  remains  of  whalebone  whales  are  found  in  this 
same  deposit,  it  is  evident  that  they  were  accustomed  to  frequent 
such  places  in  search  of  food  and  for  bringing  forth  their  young. 

Unfortunately,  the  skeleton  of  the  cetothere  hereinafter  described 
suffered  considerable  breakage  during  shipment  to  Washington  and, 
in  consequence  of  a  longitudinal  fracture,  some  of  the  centra  of  the 
thoracic  vertebrae  shown  in  the  accompanying  illustration  were 
destroyed. 

Cetotherium  furlongi,  new  species. 

Type  specimen. — Cat.  No.  26521,  Museum  of  Palaeontology,  University  of  California. 
The  skeleton  of  this  cetothere  is  remarkably  complete  in  comparison  to  previous  dis¬ 
coveries.  The  skull  has  suffered  from  erosion  and  weathering.  The  back  and  top  of 
the  braincase  have  been  eroded  away,  exposing  a  natural  brain  cast;  the  extremity  of 
the  rostrum  is  missing;  the  right  supraorbital  process  is  incomplete.  The  major  por¬ 
tion  of  the  left  mandible  and  the  proximal  end  of  the  right  are  present.  7  cervical, 
12  dorsal,  and  10  lumbar,  and  9  caudal  vertebrae  are  preserved  in  the  slab  of  sand 
stone.  The  whole  or  portions  of  17  ribs  are  intermingled  with  the  vertebrae.  The 
left  scapula,  humerus,  radius,  and  ulna,  although  articulating,  have  been  washed 
backward  and  are  overlain  by  three  of  the  lumbar  vertebrae. 

Type  locality. — The  occurrence  is  as  follows:  near  latitude  36°  1'  North,  and  longi¬ 
tude  120°  32'  West,  in  Stone  Canyon,  southeast  of  the  town  of  King  City,  Monterey 
County,  California.  Section  14,  Township  22  South,  Range  13  East,  Priest  Valley 
Quadrangle,  U.  S.  Geological  Survey. 

1  D.  S.  Jordan  and  J.  Z.  Gilbert,  Fossil  fishes  of  the  Miocene  (Monterey)  formations,  Leland 
Stanford  Junior  Univ.  Publ.,  Univ.  Series,  pp.  14,  25,  1919. 


Fossil  Cetotheres. 


39 


Horizon. — A  fine-grained,  impure,  calcareous  sandstone  of  a  greenish-gray  color 
which  underlies  the  coal  strata  in  Stone  Canyon.  According  to  Mr.  W.  N.  Nichols,  a 
graduate  student  in  the  Department  of  Geology,  University  of  California,  this  region 
show's  considerable  evidence  of  faulting  and  the  sandstone-coal  formation  is  a  block 
lying  between  serpentines  of  Franciscan  age.  Vaqueros  formation,  Middle  Miocene 
or  Helvetian  stage. 

From  long-continued  exposure  in  the  canyon,  the  upper  part  of  the  braincase  is 
missing,  having  been  destroyed  by  weathering.  By  making  due  allowance  for  the  miss¬ 
ing  caudal  vertebrae  and  for  the  intervertebral  cartilages,  it  was  found  that  the  com¬ 
plete  skeleton  of  this  cetothere,  including  the  skull,  measures  approximately  16  feet. 
Numerous  specimens  of  cetotheres  have  been  collected  in  various  formations  in  other 
countries  and  there  is  some  difference  of  opinion  regarding  their  validity.  For  the 
purposes  of  the  present  paper,  only  those  based  on  fairly  complete  skulls  will  be  con¬ 
sidered  in  making  comparisons. 

Skull. 

In  general  form,  the  skull  (text-fig.  1)  of  this  species  agrees  in  many  details  with 
that  of  Cetotherium  rathkii,1  although  it  is  nearly  twice  the  size  of  the  latter.  Detailed 
comparisons  of  many  structures  will  be  impossible  on  account  of  circumstances  con¬ 
nected  with  the  preservation  of  the  specimen.  The  ventral  surface  of  this  skull  is 
crushed  and  the  outlines  of  most  of  the  elements  and  their  sutures  are  obliterated. 
Close  scrutiny  failed  to  reveal  any  points  of  interest.  From  a  ventral  view  in  its  present 
condition,  the  skull  presents  a  flat  surface  without  any  indication  of  distinct  elements. 
The  various  bones  were  telescoped  into  one  another,  compressed  together  by  the  great 
weight  of  the  overlying  strata,  and  solidified  or  fossilized  into  a  compact  more  or  less 
homogeneous  mass.  Even  the  tympanic  bones  were  not  visible,  but  after  removing 
some  of  the  overlying  bone  which  had  shifted  from  its  original  position  by  fortuitous 
circumstances,  the  flattened  involucrum  of  the  right  tympanic  was  discovered  and 
removed.  The  horizontal  ventral  surface  of  each  maxilla  was  marked  by  shallow 
curved  grooves  for  lodging  the  bases  of  the  blades  of  baleen  which  depend  from  the 
roof  of  the  mouth.  These  ridges  may  be  observed  on  the  matrix,  although  the  cor¬ 
responding  portion  of  the  rostrum  is  missing. 

Compared  with  Cetotherium  moreni2  the  cranium  is  relatively  longer  and  narrower, 
with  a  more  rounded  intertemporal  region,  a  more  noticeable  interdigitation  of  rostral 
and  cranial  elements,  and  apparently  with  a  supraoccipital  shield  which  is  not  so 
strongly  triangular  in  outline  or  at  least  is  shorter.  The  lateral  crests  of  the  triangular 
supraoccipital  shield  are  well  developed  in  Cetotherium  moreni.  In  this  last-mentioned 
species,  the  distance  between  the  nasal  aperture  and  the  condyles  is  more  than  one- 
third  of  the  total  length  of  the  skull,  while  in  furlongi  it  is  somewhat  less  than  one- 
third.  Lydekker  estimates  the  length  of  the  nasals  in  the  skull  of  moreni  to  be  8 
or  9  inches,  while  those  of  the  present  specimen  were  no  doubt  less  than  5  inches.  In 
general  appearance,  this  skull  agrees  more  closely  with  Cetotherium  rathkii  than  with 
Cetotherium  moreni.  The  bases  of  the  nasals  in  C.  rathkii  are  in  the  same  level  as  the 
most  anterior  portion  of  the  curved  posterior  margin  of  the  supraorbital  processes. 

The  form  and  dimensions  of  the  rostrum  are  not  fully  known.  From  the  impres¬ 
sions  in  the  matrix  and  the  outlines  of  the  bones  comprising  the  base  of  the  rostrum 
it  is  fairly  certain,  however,  that  the  maxillae  were  very  large  bones.  They  formed  the 

1  J.  F.  Brandt,  L’Institut,  Paris,  No.  502,  p.  270,  August  10,  1843;  Bull.  Acad.  Sci.  St.  Peters- 
bourg,  vol.  1,  p.  146,  1843;  Untersuchungen  ueber  die  fossilen  und  subfossilen  Cetaceen 
Europa’s,  Mem.  Acad.  Imp.  Sci.  de  St.  Petersbourg,  ser.  7,  vol.  20,  No.  1,  pp.  68-85,  pis.  1-4, 
1873;  P.  J.  Van  Beneden  and  Paul  Gervais,  Osteographie  des  Cetaces  vivants  et  fossiles,  Paris, 
Atlas,  pi.  17,  figs.  6-7,  1880. 

2  R.  Lydekker,  Contributions  to  a  knowledge  of  the  fossil  vertebrates  of  Argentina:  II.  Cetacean 
skulls  from  Patagonia,  Anales  del  Museo  de  La  Plata,  vol.  2  for  1893,  pp.  2-4,  pi.  1,  figs.  1, 
la,  16,  2,  April  1894. 


40  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


major  portion  of  the  rostrum.  On  their  dorsal  aspect  the  maxillae  are  slightly  de¬ 
pressed  in  front  of  the  supraorbital  processes;  the  postero-mesial  or  ascending  processes 
are  narrow  and  are  suturally  united  with  the  frontals.  These  processes  of  the  maxillae 
are  separated  from  each  other  by  the  corresponding  processes  of  the  premaxillae  and 
by  the  nasals.  Posteriorly,  the  narrow  ascending  processes  of  the  maxillae  do  not 
extend  beyond  the  base  of  the  nasals.  The  internal  margin  of  each  maxilla  was  in 
contact  with  the  premaxilla  for  practically  the  entire  length.  An  antorbital  process 
can  be  observed  on  the  left  maxilla,  but  it  has  been  largely  destroyed  on  the  opposite 
bone.  The  lateral  border  of  the  maxilla  is  thin  and  blade-like,  differing  here  but 
slightly  in  contour  as  well  as  in  general  proportions  from  Cetotherium  moreni. 

Of  the  premaxillae  little  can  be  said.  They  extend  backward  as  far  as  the  posterior 
margins  of  the  nasals;  they  are  widely  divergent  in  the  region  of  the  nasal  apertures 
and,  although  they  converge  anteriorly  without  any  marked  horizontal  increase  in 
thickness,  there  is  nothing  peculiar  about  them  to  suggest  that  the  extremities  were 
unlike  those  of  Cetotherium  moreni.  Posteriorly,  the  premaxillae  are  narrow  as  viewed 
from  above,  with  their  greatest  diameter  in  a  dorso-ventral  direction  and  presenting  a 
slight  sigmoid  curve.  They  probably  projected  anteriorly  beyond  the  maxillae  as 
in  the  last-mentioned  species.  Along  its  entire  external  border,  the  premaxilla  is 
closely  applied  to  the  corresponding  surface  of  the  maxilla.  They  are  separated  from 
each  other  at  the  widest  point  of  their  curved  internal  margins  by  an  interval  of  96.5 
mm. 

The  supraorbital  processes  are  relatively  narrow  at  the  base  and  slope  gradually 
downward  and  outward  from  the  level  of  the  interorbital  region.  Each  process  ex¬ 
hibits  a  slight  sagittal  arch,  posterior  to  which  the  surface  is  depressed  and  as  a  whole 
slopes  backward  in  a  moderate  curve.  The  anterior  border  of  this  process  curves 
downward  and  forward  in  a  more  or  less  regular  curve.  The  preorbital  projection  is 
short  and  rounded  while  the  postorbital  is  rather  massive,  thick,  and  projects  back¬ 
ward  above  the  zygomatic  process  of  the  squamosal.  The  frontal  bones  are  relatively 
deep  and  meet  in  a  vertical  plane  behind  and  below  the  nasal  bones.  They  do  not 
contribute  any  of  the  outer  surface  of  the  braincase  in  the  intertemporal  region.  The 
frontals,  as  remarked  above,  are  overridden  in  the  interorbital  region  by  the  extremities 
of  the  maxillae,  premaxillae,  and  nasals.  There  are  no  definite  grooves  for  lodging 
the  extremities  of  the  nasals,  but,  from  the  shape  of  the  sinus,  it  is  evident  that  they 
were  relatively  narrow  and  closely  approximated,  and  their  actual  length  is  more  or 
less  problematical. 

In  front  of  the  supraoccipital  shield,  the  parietals  meet  mesially  in  a  linear  suture 
and  comprise  the  intertemporal  region.  Although  the  surfaces  of  the  parietals  are 
worn  in  this  region,  there  are  no  indications  which  would  suggest  the  presence  of  a 
sagittal  crest.  The  parietals  are  suturally  united  with  the  supraoccipital  posteriorly 
and  override  the  frontals  anteriorly.  The  relations  between  the  parietal  and  frontal 
belowr  the  supraorbital  process  are  not  clear.  In  most  balaenopterine  whales,  the 
parietals  override  the  frontals  at  the  base  of  the  supraorbital  processes  and  small 
projections  of  the  former  underlap  the  latter  at  the  same  level  below  these  processes. 
No  doubt  similar  relations  of  these  two  elements  characterized  this  Miocene  cetothere. 

The  apex  and  upper  portion  of  the  supraoccipital  is  missing,  but  the  curvature  of  the 
posterior  borders  of  the  temporal  fossae  and  the  shape  of  this  element  at  the  base 
indicate  that  its  sides  curved  obliquely  upward,  but  whether  the  apex  was  pointed  or 
rounded  can  not  be  determined.  In  a  back  view  of  the  skull  it  is  seen  that  the  supra¬ 
occipital  slopes  obliquely  forward  and  upward.  The  supraoccipital  probably  w^as  con¬ 
cavo-convex,  and  its  slanting  lateral  margins  meet  the  parietals  and  probably  overlap 
them  to  some  extent.  It  is  evident  that  the  most  anterior  point  of  the  supraoccipital 
shield  lies  considerably  behind  the  level  of  the  orbit  and  probably  also  behind  the  level 
of  the  foramen  ovale.  The  condyles  are  missing  and  the  lateral  margins  of  the  ex- 
occipitals  are  imperfect. 


' 

' 

■  -S 


t 


•  • 


Fig.  1. — Dorsal  view  of  type  skull  and  mandibles  of 
Cetothenum  furlongi.  Cat.  No.  26,521  Palaeont. 
Mus.,  Univ.  Calif.  Ant.  pr.,  antorbital  process  of 
maxilla;  Cer.,  natural  cast  of  lobe  of  cerebellum; 
Ex.  oc.,  exoccipital;  Fr.,  frontal;  L.  M.,  left  man¬ 
dible;  Max., maxilla;  Pa., parietal ;  Pmx., premaxilla; 
R.  M.,  right  mandible;  Sq.,  squamosal;  S.  or.  pr., 
supraorbital  process  of  frontal;  Zgg.,  zygomatic 
process  of  squamosal. 


m//M 


Fossil  Cetotheres. 


41 


The  squamosals  were  rather  large  bones,  which  were  suturally  united  with  the 
parietals  above  and  the  pterygoids  in  front.  Their  zygomatic  processes  are  relatively 
long  and  narrow,  curving  outward  and  forward.  The  squamous  portion  of  this  bone 
is  thick  and  apparently  meets  the  parietal  edge  to  edge;  it  is  possible,  however,  that 
the  squamosal  overlaps  the  posterior  part  of  the  ventral  edge  of  the  parietal.  The 
anterior  extremity  of  the  squamous  portion  is  prolonged  forward,  inward,  and  slightly 
downward  as  the  bifid  pterygoid  process.  The  upper  fork  of  the  latter  overlaps  the 
upper  part  of  the  pterygoid,  posterior  to  and  below  the  alisphenoid;  the  lower  fork, 
the  falciform  process,  meets  that  portion  of  the  pterygoid  which  forms  the  external 
boundary  of  the  pterygoid  fossa.  Between  the  two  forks  of  the  squamosal  and  the 
above-mentioned  portions  of  the  pterygoid  is  a  notch  which  represents  the  foramen 
ovale.  The  squamosals  and  their  processes  form  the  posterior  and  outer  borders  of  the 
temporal  fossae.  The  left  zygomatic  process  is  complete  and  abuts  against  the  post¬ 
orbital  projection  of  the  supraorbital  process.  The  zygomatic  process  tapers  anteriorly, 
with  the  external  margin  as  seen  from  above,  curving  forward  in  a  regular  curve  in 
marked  contrast  with  the  bi-convexity  of  the  same  surface  on  that  of  Cetotherium 
rathkii.  The  glenoid  articular  surface  extends  over  upon  the  outer  face  of  the  zygoma¬ 
tic  process.  In  direction  the  anterior  portion  of  this  surface  is  strongly  oblique.  The 
postglenoid  process  is  long,  directed  more  downward  than  backward. 

The  jugal  is  missing  and  the  lachrymal  can  not  be  recognized  if  present.  The 
extremity  of  the  vomer  is  missing,  and  the  proximal  portion  takes  the  form  of  an  open 
V-shaped  trough  as  far  backward  as  the  nasal  passages,  beyond  which  in  all  mysti- 
cetes  known  to  the  winter  it  flattens  out  on  the  ventral  face  of  the  basicranium  to 
sheath  the  basisphenoid. 

The  exposed  natural  brain-cast  gives  some  idea  of  the  original  appearance  of  the 
posterior  portion  of  the  brain.  The  lobes  of  the  cerebellum  are  large  and  bulging, 
separated  mesially  by  a  sinus,  and  bounded  posteriorly  by  the  medulla  oblongata. 
These  lobes  helped  to  mould  the  lateral  contour  of  the  braincase. 

Mandibles. 

Comparison  of  the  type  mandible  of  Eschrichitus  davidsonii  Cope1  with  the  mandibles 
of  this  cetothere  unfortunately  will  not  prove  very  satisfactory  for  several  reasons. 
In  the  first  place,  the  nature  of  the  formation  from  which  Cope’s  specimen  was  obtained 
was  not  given.  According  to  the  label  on  the  specimen  it  was  found  in  digging  a  well 
at  San  Diego  at  a  depth  of  74  feet  below  the  surface.  The  type  of  Eschrichitus  david¬ 
sonii  Cope  consists  of  a  section  of  the  left  mandible  327  mm.  in  length,  and  the  greatest 
depth  of  this  fragment  is  99  mm.  It  now  bears  Cat.  No.  12922  in  the  collection  of 
the  Academy  of  Natural  Sciences  of  Philadelphia.  In  general  proportions  it  agrees 
fairly  well  with  those  of  this  cetothere,  but  so  do  others  from  Miocene  formations  on 
the  Atlantic  Coast.  The  characters  used  by  Cope,  such  as  the  point  of  termination  of 
the  external  foraminal  series  and  the  peculiarities  of  the  canalis  mandibularis  can  not 
be  ascertained  from  either  of  these  mandibles.  The  angle  and  condyle  of  all  three  of 
the  mandibles  are  missing;  so  also  is  the  coronoid  process.  Approximately  three- 
fourths  of  the  left  mandible  (text-fig.  1)  of  this  cetothere  is  preserved.  At  the  broken 
extremity,  the  mandible  measures  85  mm.  in  depth,  the  greatest  depth  of  the  mandi¬ 
bular  canal  being  74  mm.  and  the  greatest  breadth  30  mm.  The  internal  surface  of 
the  mandible  is  plane  on  the  proximal  half,  but  distally  it  becomes  more  convex. 
Externally,  the  mandible  is  more  or  less  convex,  being  broader  below  the  middle  than 
above.  The  mandible  is  bowed  to  a  slight  extent  and  the  inferior  margin  is  nearly 
straight.  The  internal  foramina  are  relatively  small,  about  an  inch  apart,  and  form 
a  series  which  follows  the  upper  margin.  The  foramina  in  the  external  series  are  large 
and  separated  by  rather  wide  intervals.  Behind  the  coronoid  the  anterior  end  of  the 

i  E.  D.  Cope,  On  an  extinct  whale  from  California,  Proc.  Acad.  Nat.  Sci.  Philadelphia,  pp. 
29-30,  1872. 


42  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


cavity  on  the  internal  face  of  the  mandible  is  filled-in  with  matrix,  and  the  loss  of  the 
posterior  extremity  prevents  accurate  comparison  with  European  specimens. 


Table  of  measurements. 

mm. 

Total  length  of  skull,  as  estimated . 1,240 

Breadth  of  skull  across  anterior  ends  of  zygomatic  processes .  545 

Greatest  breadth  of  skull  across  lateral  margins  of  exoccipitals  estimated .  370 

Greatest  transverse  width  of  temporal  fossa .  188 

Greatest  antero-posterior  diameter  of  temporal  fossa .  150 

Least  breadth  of  braincase  in  intertemporal  region .  154 

Greatest  breadth  of  skull  across  supraorbital  processes .  540 

Greatest  antero-posterior  diameter  of  left  supraorbital  process  at  extremity .  213 

Distance  from  base  of  nasals  to  condyles,  estimated .  387 

Depth  of  rostrum  at  point  where  broken  off . .  107 

Greatest  breadth  of  premaxilla  at  level  of  external  nasal  apertures .  15 

Breadth  of  left  maxilla  in  front  of  antorbital  process  of  that  bone .  185 

Greatest  length  of  left  zygomatic  process .  240 

Depth  of  left  zygomatic  process  at  extremity .  36.9 

Distance  from  preorbital  portion  of  supraorbital  process  to  postglenoid  process  of  squa¬ 
mosal .  410 

Distance  from  postorbital  projection  of  left  supraorbital  process  to  base  of  corresponding 

nasal .  298 

Greatest  length  of  tympanic  bulla .  117 

Greatest  breadth  of  involucrum .  38 

Total  length  of  left  mandible  as  preserved .  974 

Greatest  depth  of  left  mandible  at  point  where  broken  off .  85 

Greatest  breadth  of  left  mandible  at  point  where  broken  off .  56.2 

Greatest  depth  of  left  mandible  at  proximal  end .  102.5 

Least  breadth  of  left  mandible  at  proximal  end .  25  + 


Vertebrae. 

All  of  the  cervical  vertebrae  (text-fig.  2)  of  this  fossil  cetothere  are  free  and  distinct. 
They  are  exceedingly  thin  in  an  antero-posterior  direction  and  this  peculiarity  is 
accentuated  by  the  relative  lengths  of  the  slender  transverse  processes.  In  the  living 
Bowhead  Whale,  Balaena  mysticetus,  and  the  North  Atlantic  Right  Whale,  Eubalaena 
glacialis,  the  7  cervical  vertebrae  are  normally  fused  together  to  form  a  single  mass  and 
are  so  modified  by  this  telescoping  that  it  is  not  easy  to  recognize  their  identity. 
Occasionally  the  seventh  cervical  is  free.  The  pedicles  of  the  neural  arches  of  all  of 
the  cervicals  are  usually  distinct,  but  the  spines  and  upper  portions  of  the  arches  of  the 
second  to  sixth  inclusive  are  fused  into  a  solid  mass.  The  balaenopterine  whales, 
however,  differ  in  having  all  of  the  cervicals  free  and  distinct.  As  an  individual 
peculiarity,  two  or  more  cervicals  may  be  irregularly  ankylosed  together. 

The  ankylosis  of  the  cervical  vertebrae  and  their  fusion  into  a  compact  immovable 
mass  is  considered  to  be  the  culmination  of  an  evolutionary  trend  toward  the  shorten¬ 
ing  of  the  neck.  The  increase  in  the  size  and  proportions  of  the  skull,  the  out-bowing 
of  the  lower  jaws,  and  the  development  of  long  blades  of  baleen  depending  from  the 
roof  of  the  mouth,  require  a  firm  axis  upon  which  the  skull  can  rotate  and  which  at 
the  same  time  will  support  an  enormous  increase  in  the  weight  of  the  skull  suspended 
from  it.  This  support  could  be  secured  by  the  development  of  massive  cervicals  or 
by  the  shortening  of  the  neck,  and  ultimately  by  the  fusion  of  the  7  cervicals.  In  the 
case  of  any  pelagic  mammal  having  feeding  habits  similar  to  those  of  the  whalebone 
whales,  flexibility  of  the  neck  is  not  absolutely  necessary  to  its  welfare;  hence  the 
short  neck  appears  to  fulfill  the  necessary  requirements  for  cetaceans  with  relatively 
large  skulls. 

In  these  Miocene  cetotheres  in  which  the  cervical  vertebrae  are  separate,  it  is  appar¬ 
ent,  from  the  dorsal  extension  of  the  opposing  articular  facets  on  the  atlas  and  axis, 
that  any  rotary  movement  about  the  odontoid  is  very  limited.  On  the  other  hand, 
the  articular  surfaces  of  the  two  occipital  condyles  are  convex  and  taken  together  form 
a  sub-hemispherical  protuberance  which  fits  into  the  basin-like  atlas.  The  crescentic 


Fossil  Cetotheres. 


43 


shape  of  the  two  articular  facets  on  the  atlas  which  comprise  the  basin  and  bound  the 
spinal  cord  allows  some  freedom  of  movement  for  the  head,  chiefly  in  an  up-and-down 
or  side-to-side  direction,  and  also  permits  a  limited  rotary  movement.  Some  side-to- 
side  movement  is  permitted  in  most  mammals  by  the  flexure  of  the  cervical  series  as  a 
whole  but,  inasmuch  as  all  of  these  vertebrae  are  excessively  shortened,  any  movement 
of  this  kind  is  effectually  restricted. 

The  atlas  is  incomplete,  the  upper  portion  having  been  weathered  away  until  nothing 
more  than  a  shell-like  strip  of  the  inferior  region  remains.  While  agreeing  with  certain 
specimens  from  the  Calvert  formation  in  size,  this  atlas  differs  in  some  details  of  form. 
Attention  should  be  directed  to  the  presence  of  a  short,  lower,  transverse  process  (para- 
pophysis)  and  to  the  curvature  of  the  anterior  and  posterior  borders.  The  atlas  is 
relatively  deep  antero-posteriorly  in  comparison  to  the  succeeding  cervicals,  the  length 
being  less  than  one-fifth  of  its  greatest  breadth.  In  comparison  to  an  atlas  from 
the  Calvert  formation  near  Plum  Point,  Maryland,  it  is  about  equal  in  size,  but  the 
transverse  processes  are  deflected  more  strongly  backward  and  the  concave  articular 
surfaces  for  the  occipital  condyles  are  nearly  confluent  at  their  inferior  edges,  or  at 
least  are  not  separated  by  a  mesial  depression  or  elevation.  The  posterior  border  of 
the  atlas  as  viewed  from  above  is  distinctly  concave  and  there  is  no  trace  of  a  triangular 
projection  which  would  fit  under  the  odontoid  process  of  the  axis.  The  posterior  mar¬ 
gin  of  the  atlas  from  Maryland  is  slightly  convex  and  there  is  a  distinct  triangular  pro¬ 
jection  mesially  on  the  inferior  margin.  The  last-mentioned  atlas  has  short,  stout, 
tapering,  imperforate  transverse  processes.  From  a  posterior  view,  the  body  of  this 
atlas  is  seen  to  be  much  deeper  than  in  front,  and  the  flattened  articular  surfaces  for 
the  axis  are  more  nearly  crescentic  in  outline.  In  front  of  the  atlas  is  a  slender  bone 
which  appears  to  be  the  right  stylohyal. 

At  this  point,  attention  should  be  directed  to  the  fact  that  the  illustration  (text-fig. 
2)  accompanying  this  description  shows  the  outlines  of  the  vertebrae  only  in  so  far  as 
they  have  been  exposed  by  the  preparator.  For  this  reason,  the  transverse  processes 
of  the  cervical  vertebrae  especially  appear  to  be  more  asymmetrical  than  they  would 
if  the  vertebrae  had  been  freed  from  the  matrix  and  arranged  in  accordance  with  their 
normal  position  in  the  series.  At  first  glance  the  axis  of  this  specimen  appears  to  be 
somewhat  asymmetrical,  the  transverse  process  of  the  left  side  being  more  strongly 
twisted,  directed  obliquely  backward  and  then  curving  forward,  but  this  condition 
unquestionably  has  resulted  from  crushing.  The  transverse  process  of  the  right  side 
also  presents  an  irregular  curvature.  The  axis  has  a  broad  triangular  body,  a  short, 
thick  odontoid  process,  and  wide,  perforated,  wing-like  transverse  processes,  the  per¬ 
foration  being  rather  large;  the  high  massive  arch  and  spine  are  missing. 

The  other  cervical  vertebrae  have  thin  sub-rectangular  centra,  and  very  long,  slender, 
transverse  processes  composed  of  an  upper  bar  (diapophysis)  and  a  lower  bar  (para- 
pophysis),  which  are  widely  separated  at  the  base  and  inclose  a  space  somewhat  smaller 
than  the  centrum.  The  extremities  of  these  2  above-mentioned  bars  are  not  united 
on  the  last  3  cervicals.  The  neural  arches  and  spines  of  all  of  these  cervicals  have  been 
eroded  away.  The  neural  canals  of  most  cetotheres  are  exceedingly  low  in  comparison 
to  their  breadth.  The  transverse  processes  of  the  seventh  cervical  are  directed  forward 
throughout  most  of  their  length  but  recurved  near  the  extremity.  This  curvature 
indicates  a  somewhat  restricted  flexibility  of  the  neck,  that  is  from  a  side  to  side  direc¬ 
tion,  for  the  long  transverse  processes  of  the  first  dorsal  are  also  directed  obliquely  for¬ 
ward.  The  centra  of  the  third  to  seventh  cervical  vertebrae  inclusive  progressively 
increase  in  thickness,  that  of  the  last  being  almost  one-third  greater  than  that  of  the 
third. 

Some  variation  in  the  total  number  of  thoracic  and  caudal  vertebrae  exists  in  certain 
of  the  living  Mysticeti,  but  the  vertebral  formulae  of  the  several  species  now  recog¬ 
nized  show  an  even  greater  range  of  variation.  As  yet,  we  do  not  know  what  to  expect 
in  the  various  fossil  forms  which  already  have  been  made  known  from  incomplete  skele- 


44  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


tons  or  skulls.  For  convenience  in  comparison,  the  vertebral  formulae  of  the  whale¬ 
bone  whales,  living  and  extinct,  are  assembled  in  the  following  table,  together  with  the 
total  lengths  of  adults  of  these  cetaceans. 


Total 
length1 
(in  flesh). 

C. 

D. 

L. 

Ca. 

Total 

number 

verte¬ 

brae. 

Authority. 

Balaena  mysticetus . 

ft.  in. 

65 

7 

14 

10 

23 

54 

Gray,  1866. 

Balaenula  balaenopsis . 

16  4 

7 

13 

10 

21 

51 

Van  Beneden, 

Eubalaena  australis . 

268 

7 

15 

11 

21 

54 

1878. 

Hector,  1872. 

Eubalaena  glacialis . 

48-54 

7 

14 

11 

24 

56 

Allen,  1908. 

Neobalaena  marginata . 

320 

7 

18 

1 

14 

40 

Oliver,  1922. 

Mesocetus  hungaricus . 

204 

7 

12 

11 

14 

46 

Kadic,  1907. 

Cetotherium  furlongi . 

16 

7 

12 

10 

12 

41 

Kellogg. 

Rhachianectes  glaucus . 

43  2.4 

7 

14 

12 

23 

56 

Andrews,  1914. 

Megaptera  nodosa . 

47 

7 

14 

10-11 

19-22 

51-54 

True,  1904. 

Balaenoptera  cortessii . 

22  4 

7 

12 

11 

10 

40 

Cuvier,  1836. 

Balaenoptera  acuto-rostrata .  . . 

Balaenoptera  borealis . 

(  427 10.5 

7 

11 

12-13 

17-20 

47-49 

True,  1904. 

\333 

41  3.75 

7 

14 

13 

23 

57 

Andrews,  1916. 

Balaenoptera  physalus . 

f387 
\570  8 

7 

15 

15 

25 

62 

Oliver,  1922. 

Sibbaldus  musculus . 

&72  7 

7 

15 

14 

28 

64 

Oliver,  1922. 

1  Most  of  these  measurements  are  taken  from  tip  of  upper  jaw  to  notch  of  flukes;  one  or  two 
may  have  been  taken  in  a  different  way,  i.  e.,  to  tip  of  fluke,  and  in  that  case  are  “over  all” 
measurements. 

2  Gray,  1866.  3  Oliver,  1922a.  4  Turner,  1892.  6  True,  1904. 

This  specimen  has  at  least  11  dorsal  vertebrae  and  possibly  12,  for  11  have  more  or 
less  well-marked  articular  facets  at  the  distal  ends  of  the  transverse  processes  for  the 
reception  of  the  tubercula  of  the  corresponding  ribs.  The  extremities  of  the  transverse 
processes  of  the  twelfth  thoracic  vertebra  are  slightly  thickened  and  this  may  indicate 
the  attachment  of  a  pair  of  ribs.  The  heads  of  the  last  pair  of  ribs,  which  in  some  of 
the  living  balaenopterine  whales  do  not  articulate  with  a  corresponding  surface  on  the 
transverse  process  of  the  last  dorsal  vertebra,  may  also  be  unattached  to  the  vertebral 
column  of  this  skeleton.  Hence  the  actual  number  of  dorsal  vertebrae  can  not  always 
be  determined  from  the  total  number  of  vertebrae  bearing  rib  facets. 

The  first  dorsal  resembles  a  posterior  cervical  more  closely  than  do  the  following 
dorsals,  the  centrum  being  broad  and  depressed.  From  the  beginning  to  the  end  of 
the  series,  the  centra  of  the  dorsals  increase  in  length  and  this  increase  is  especially 
marked  between  the  fifth  and  sixth.  The  centra  of  the  more  posterior  dorsal  verte¬ 
brae  are  rather  cylindrical  and  distinctly  elongated.  The  epiphyses  of  these  vertebrae 
are  fully  ossified  and  completely  coalesced  with  the  centra.  On  the  first  dorsal  of 
most  cetotheres,  the  neural  canal  is  wider  in  proportion  to  its  height  than  in  any  of 
the  others.  No  neural  spines  are  preserved,  but  no  doubt  they  were  high,  thin,  blade¬ 
like  processes  with  the  truncated  extremities.  The  neural  canal  of  the  second  dorsal 
measures  61  mm.  in  breadth  at  the  base,  and  its  greatest  height  anteriorly  is  37.  mm. 
The  transverse  processes  of  the  first  8  dorsals  are  directed  obliquely  forward,  those  of 
the  first  more  so  than  the  following  ones,  and  those  of  the  last  4  outward.  From  before 
backwards,  these  processes  increase  in  breadth  and  tend  to  become  shorter  as  they 
approach  the  seventh  dorsal  vertebra.  From  this  dorsal  posteriorly,  the  transverse 
processes  gradually  lengthen. 

Beginning  with  the  sixth  dorsal,  the  transverse  processes  appear  to  be  constricted 
mesially,  or  rather  their  distal  ends  expand  in  an  anteroposterior  direction;  those  of 


Fossil  Cetotheres. 


45 


the  eleventh  dorsal  are  more  than  twice  as  broad  as  those  of  the  first.  The  ends  of  the 
transverse  processes  of  the  eighth  to  tenth  dorsals  inclusive  are  deeply  excavated. 
These  articular  facets  lie  horizontal  to  the  long  axis  of  the  centrum  while  those  of  the 
anterior  dorsals  incline  obliquely  upward. 

The  lumbars  resemble  the  posterior  dorsals  in  general  appearance,  but  differ  in  that 
the  ends  of  their  transverse  processes  do  not  bear  ribs.  As  usual  in  these  cetaceans,  the 
centra  become  more  massive  toward  the  caudal  series.  The  transverse  processes  of 
the  anterior  lumbars  are  directed  outward  while  those  of  the  posterior  lumbars  curve 
forward.  On  the  inferior  face  of  these  thoracic  vertebrae,  there  is  a  mesial  longitudinal 
carina.  This  keel  increases  in  height  toward  the  end  of  the  series.  Furthermore, 
attention  should  be  directed  to  the  fourth  to  eighth  lumbars  inclusive,  in  which  the 
centrum  is  distinctly  constricted  behind  the  transverse  processes. 


Fig.  3. — Dorsal  view  of  tenth  lumbar  vertebra  of  Cetotherium  furlongi.  Cat.  No.  26521, 

Palaeont.  Mus.  Univ.  Calif. 


Turning  again  to  the  first  three  lumbars,  it  will  be  noted  that  the  transverse  pro¬ 
cesses  are  proportionately  narrower  and  longer  than  those  of  any  of  the  following  ver¬ 
tebrae,  and  that  the  extremities  of  these  processes  do  not  project  forward  beyond  the 
level  of  the  anterior  epiphyses.  Beginning  with  the  fourth  lumbar,  the  anterior  and 
posterior  margins  of  the  transverse  processes  are  characterized  by  a  strong  curvature 
which  carries  the  anterior  angle  of  the  extremity  beyond  the  level  of  the  anterior  epi¬ 
physis.  With  the  broadening  of  the  transverse  process,  an  indentation  is  produced 
anteriorly  at  the  base.  This  indentation  is  well  marked  on  the  seventh  lumbar,  and 
increases  in  depth  on  each  succeeding  vertebra  and  apparently  reaches  its  maximum  de¬ 
velopment  on  the  first  caudal.  The  seventh  and  tenth  lumbars  were  freed  from  the 
matrix  and  may  serve  to  illustrate  the  extent  and  direction  of  the  distortion  which 
characterizes  all  of  these  vertebrae.  To  a  still  greater  degree,  the  sixth  lumbar  is  com¬ 
pressed  in  a  dorso-ventral  direction,  the  maximum  thickness  of  the  centrum  as  pre¬ 
served  being  about  80  mm.  This  lumbar  lay  above  the  scapula.  The  seventh  and 
tenth  lumbars  were  not  superimposed  on  any  other  bones  but  nevertheless  they  have 
been  flattened  to  some  extent.  From  a  dorsal  view  (text-fig.  3),  the  transverse  pro¬ 
cesses  of  the  tenth  lumbar  appear  asymmetrical  and  the  distortion  of  the  centrum  is 
from  right  to  left.  The  extremities  of  these  transverse  processes  are  not  complete 


46  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


and  the  anterior  angles  are  missing.  The  upper  portion  of  the  neural  arches  and  all 
of  the  spine  are  missing,  but  some  idea  of  the  narrowness  of  the  neural  canal  is  afforded 
by  this  view.  There  is  a  single  longitudinal  mesial  carina  on  the  inferior  face  of  the 
centrum  (text-fig.  4),  but  this  also  is  distorted  by  crushing.  On  the  posterior  margins, 
the  notches  at  the  bases  of  the  transverse  processes  are  especially  well  marked.  The 
anterior  view  (text-fig.  5)  does  not  show  any  features  of  especial  interest.  A  lateral 
view  (text-fig.  6)  is  given  to  illustrate  the  depression  of  the  lateral  face  of  the  centrum 
above  and  below  the  transverse  process. 

The  vertebral  formulae  of  many  cetaceans  are  often  incorrectly  given,  the  discrep¬ 
ancies  noted  usually  being  attributed  to  the  inaccurate  determination  of  the  last  lum¬ 
bar  and  the  first  caudal  vertebra.  The  caudal  series  begins  with  the  first  vertebra 
which  bears  chevron  facets  on  the  posterior  end  of  the  centrum  interiorly.  The  first 
and  second  chevrons  are  usually  small,  but  the  third  bears  a  haemal  spine.  Regardless 
of  the  actual  preservation  of  the  corresponding  chevron,  the  first  caudal  usually  can 
be  determined  by  the  posterior  bifurcation  of  the  median  inferior  carina.  On  the 
preceding  lumbars,  this  carina  progressively  increases  in  width  and  depth  posteriorly. 
Here  again  some  difficulty  is  encountered  because  the  ventral  surfaces  of  these  ver¬ 
tebrae  have  not  been  exposed.  Fortunately,  the  tenth  lumbar  has  been  freed  from 
the  matrix.  An  examination  of  the  inferior  face  of  the  centrum  shows  a  widening 
of  the  longitudinal  carina  posteriorly,  but  in  view  of  the  imperfect  condition  of  the 
vertebra  it  appears  best  not  to  lay  too  much  stress  upon  this  feature.  Nevertheless, 
this  vertebra  appears  to  be  either  the  last  lumbar  or  the  first  caudal,  and  in  view  of 
the  lumbar  series  of  Mesocetus  hungaricus,1  it  is  here  given  as  the  tenth  lumbar. 

Since  the  whalebone  whales  propel  themselves  through  the  water  by  upward  and 
downward  strokes  of  the  flukes,  the  tail  usually  is  well  developed  and  consists  of  several 
vertebrae.  In  the  living  Sulphurbottom  Whale  ( Sibbaldus  musculus )  there  are  occa¬ 
sionally  as  many  as  30  caudals,  but  on  the  other  hand  only  14  caudals  comprise  the 
tail  of  the  Pigmy  Right  Whale  ( Neobalaena  marginata).  It  is  not  surprising  that  the 
caudal  series  of  this  cetothere  is  incomplete,  for  a  number  of  the  thoracic  vertebrae 
are  displaced,  but  it  is  difficult  to  determine  the  original  number ;  9  more  or  less  com¬ 
plete  caudal  vertebrae  are  preserved,  1  or  2  of  the  terminal  caudals  may  be  missing 
and  possibly  2  or  more  intermediate  ones.  A  computation  of  the  original  series  of 
caudal  vertebrae  based  upon  the  relative  lengths  of  the  centra  of  those  available  indi¬ 
cates  a  series  of  12  to  14  vertebrae.  The  centra  of  the  anterior  caudals  are  massive 
with  short,  broad,  transverse  processes  directed  outward;  the  neural  arches  probably 
had  high  spines.  The  centra  of  the  posterior  caudals  tend  to  become  more  nearly 
cylindrical  up  to  the  transitional  caudal.  This  transitional  caudal,  apparently,  is  the 
fourth  one  counting  forward  from  the  terminal  one  shown  on  text-figure  2.  It  is  con¬ 
siderably  shorter  than  the  preceding  caudal  vertebrae,  and  in  most  cetaceans  it  is  longer 
than  the  antero-posteriorly  flattened  terminal  caudals.  The  anterior  margin  of  the 
transverse  process  of  the  first  caudal  is  deeply  notched  near  the  base  and  the  lateral 
face  of  the  centrum  above  and  below  this  process  is  excavated.  The  second  caudal 
has  been  damaged  and  most  of  its  peculiarities  are  unknown.  It  possessed  broad, 
transverse  processes  perforated  near  the  center  of  the  base  by  a  foramen,  but  the 
anterior  basal  notch  is  shallower.  Only  the  cylindrical  centrum  remains  of  the  next 
caudal.  An  imperfect  chevron  which  belongs  no  doubt  with  this  caudal  is  embedded 
in  the  matrix  on  the  left  side.  The  anterior  2  of  the  remaining  6  caudals  likewise  have 
cylindrical  centra,  but  lack  transverse  processes.  On  the  left  side  of  these  2  caudals 
and  near  the  anterior  margin,  the  corresponding  chevrons  were  found.  The  lateral 
faces  of  the  eighth  and  ninth  caudal  vertebrae  were  transversed  by  a  blood-vessel  or 
nerve  which  followed  the  usual  course.  There  is  no  indication  of  a  groove,  however, 

1  O.  Kadic,  Mesocetus  hungaricus  Kadic,  eine  neue  Balaenopteridenart,  aus  dem  Miozan  von 
Borbolya  in  Ungarn,  Jahrb.  kgl.  Ungar.  Geol.  Anstalt,  Budapest,  Bd.  16,  H.  2,  pp.  21-91,  3  pis., 
70  text  figs.,  1907. 


*,!a^K 


Fossil  Cetotheres. 


47 


Fig.  4. — Ventral  view  of  tenth  lumbar  vertebra  of  Cetotherium  furlongi.  Cat.  No.  26521, 

Palaeont.  Mus.  Calif. 


Figs.  5,  6. — Tenth  lumbar  vertebra  of  Cetotherium  furlongi .  Cat.  No.  26521,  Palaeont.  Mus. 

Univ.  Calif.  Fig.  5  anterior  view;  fig.  6,  lateral  view. 


48  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


on  the  lower  portion  of  the  lateral  face,  but  near  the  middle  there  is  a  short  vertical 
canal  which  passes  through  the  substance  of  the  centrum.  Above  the  dorsal  orifice 
of  this  canal,  no  groove  can  be  found,  although  it  is  fairly  certain  that  the  blood-vessel 
or  nerve  passed  into  the  neural  canal  through  the  small  foramen  which  pierces  the 
base  of  the  neural  arch.  The  neural  arches  and  processes  of  the  caudal  vertebrae 
of  all  of  the  living  balaenopterine  whales  decrease  in  size  gradually  and  never  abruptly, 
and  no  doubt  similar  gradations  were  exhibited  by  the  caudals  of  this  cetothere.  Ac¬ 
cording  to  the  assumed  number  of  vertebrae  in  the  caudal  series,  the  neural  arches  dis¬ 
appear  on  the  eighth  caudal. 


Measurements  of  the  vertebrae  in  (millimeters) . 


Length  of 
centrum. 

Width  of 
anterior  face 
of  centrum. 

Height  of 
anterior  face 
of  centrum. 

Distance  be¬ 
tween  outer 
ends  of 
transverse 
processes. 

Greatest  antero¬ 
posterior  diam¬ 
eter  of  transverse 
process  at 
extremity. 

Atlas . 

37 

x 

x 

220 

x  — 

Axis . 

161.2 

X 

X 

242 

X 

Third  cervical . 

21 

X 

64.5 

232 

X 

Fourth  cervical . 

23.2 

X 

65 

232 

X 

Fifth  cervical . 

23  + 

X 

66 

237 

X 

Sixth  cervical . 

25.5 

X 

68 

244 

X 

Seventh  cervical .... 

30.5 

97 

68 

274 

X 

First  dorsal . 

38.5 

X 

73.5 

224 

26 

Second  dorsal . 

45 

X 

74 

210 

35 

Third  dorsal . 

51 

X 

80 

X 

35.5 

Fourth  dorsal . 

61 

X 

81 

194 

40.5 

Fifth  dorsal . 

62.5 

X 

X 

X 

31 

Sixth  dorsal . 

71 

X 

X 

211 

45 

Seventh  dorsal . 

77 

X 

X 

208 

46 

Eighth  dorsal . 

82 

X 

X 

237 

49 

Ninth  dorsal . 

89 

X 

X 

265 

60 

Tenth  dorsal . 

92 

X 

X 

304 

72 

Eleventh  dorsal . 

93 

X 

X 

350 

80 

Twelfth  dorsal . 

93 

X 

X 

360 

X 

First  lumbar . 

90+ 

X 

X 

X 

X 

Second  lumbar . 

103 

X 

78+ 

X 

X 

Third  lumbar . 

100  + 

X 

X 

X 

X 

Fourth  lumbar . 

110 

102 

85 

300  + 

X 

Fifth  lumbar . 

120 

X 

X 

335 

X 

Sixth  lumbar . 

X 

97  + 

80+ 

320 

X 

Seventh  lumbar . 

120 

113 

94 

X 

X 

Eighth  lumbar . 

130 

116 

87 

238 

X 

Ninth  lumbar . 

138 

113  + 

X 

226 

X 

Tenth  lumbar . 

137 

116.5 

95 

224  + 

101  + 

First  caudal . 

140 

113 

105 

188  + 

76  + 

Second  caudal . 

135 

106 

X 

X 

X 

Third  caudal . 

130 

100 

X 

X 

X 

Seventh  caudal . 

110 

92 

X 

X 

X 

Eighth  caudal . 

105 

89 

X 

X 

X 

Ninth  caudal . 

76 

88 

101  + 

X 

X 

Eleventh  caudal .... 

29 

69 

40 

X 

X 

Twelfth  caudal . 

X 

60 

38 

X 

X 

1  Including  odontoid  process. 


Scapula. 

In  contour  and  general  size,  the  left  scapula  (text-fig.  2)  agrees  very  closely  with 
tne  left  scapula  of  Cetotherium  klinderi.1  The  ventral  or  internal  surface  has  been 
exposed  along  its  suprascapular  or  vertebral  margin,  but,  unfortunately,  the  fourth, 

1  J.  F.  Brandt,  Mem.  Acad.  Imp.  Sci.  de  St.  Petersbourg,  ser.  7,  vol.  20,  No.  1,  p.  92,  pi.  5 
tig.  14a,  1873. 


Fossil  Cetotheres. 


49 


fifth,  and  sixth  lumbars  are  superimposed  over  the  lower  portion.  The  axillary  margin 
and  inferior  angle  are  thus  hidden  from  view.  The  vertebral  margin  of  the  scapula  is 
regularly  convex  in  contrast  to  the  flattening  which  characterizes  the  central  portion 
of  this  border  in  most  of  the  living  species  of  the  genus  Balcienoptera.  Most  of  the 
slender  cylindrical  coracoid  process  has  been  destroyed.  The  acromion  is  well  devel¬ 
oped,  rather  broad,  and  directed  more  nearly  outward  than  downward.  The  neck 
of  this  scapula  is  relatively  broad  and  the  glenoid  cavity  for  the  head  of  the  humerus 
is  rather  large.  Above  the  acromion,  the  anterior  margin  is  nearly  vertical  or  inclined 
very  slightly  forward.  Consequently,  the  supra-metacromial  notch  is  lacking. 


Measurements  of  the  scapula.  mw< 

Distance  from  anterior  angle  to  inferior  angle,  measured  in  a  straight  line .  380  + 

Distance  at  widest  point  from  vertebral  margin  to  head  of  scapula .  210  + 

Distance  from  anterior  (coracoid)  margin  of  scapula  to  tip  of  acromion .  80  + 


Humerus. 

Unfortunately  the  humerus  lies  beneath  the  third  and  fourth  lumbars  and  is  crushed 
in  such  a  way  that  little  can  be  learned  regarding  its  peculiarities.  In  comparison  to 
humeri  from  the  Calvert  formation  of  Maryland,  it  presents  no  striking  differences. 
The  head  is  large  and  rounded  without  any  apparent  neck,  and  the  lesser  tubercle  pro¬ 
jects  dorsad  above  it.  The  total  length  of  the  humerus  was  approximately  200  mm. 
and  the  greatest  breadth  of  the  proximal  end  as  preserved  is  116  mm. 

Radius  and  Ulna. 

The  proximal  ends  of  the  long  slender  radius  and  ulna  also  underlie  the  third  and 
fourth  lumbars.  The  extremities,  however,  exhibit  a  closer  agreement  with  the 
balaenopterine  whales  than  with  Balaena.  The  shaft  of  the  ulna  is  slightly  narrower 
than  that  of  the  radius.  Both  are  characterized  by  expanded  distal  extremities.  The 
olecranon  process  of  the  ulna  lies  beneath  the  transverse  process  of  the  fourth  lumbar, 
and  it  was  thought  advisable  not  to  attempt  any  further  removal  of  the  maxtrix  to 
facilitate  a  study  of  this  process.  The  estimated  total  length  of  the  ulna  including  the 
olecranon  process  is  282  mm.  and  the  breadth  of  the  distal  extremity  is  70  mm.  The 
anterior  face  of  the  shaft  of  the  ulna  is  rounded;  the  external  and  internal  faces  con¬ 
verge  posteriorly  to  form  a  thin  margin.  The  shaft  of  the  radius  is  rather  stout, 
slightly  thicker  than  that  of  the  ulna,  and  measures  273  mm.  in  length,  while  the  distal 
extremity  measures  83  mm.  in  breadth.  Some  of  the  carpals  of  this  flipper  and  the 
right  scapula  underlie  the  radius  and  ulna  in  the  matrix. 

Ribs. 

Nine  of  the  ribs  on  the  right  side  and  8  of  those  on  the  left  side  are  embedded  in  the 
matrix  (text-fig.  2).  As  will  become  apparent,  the  ribs  do  not  lie  in  their  normal  posi¬ 
tion,  although  those  on  opposite  sides  supplement  each  other  to  some  extent  and  by 
utilizing  both  series  a  composite  description  can  be  given.  The  possibility  of  in¬ 
correctly  allocating  the  tangled  mass  of  ribs  on  both  sides  is  especially  great  because 
of  obvious  differences  in  the  curvature  of  the  shafts  and  in  the  presence  of  a  distinct 
angle  on  some  of  the  anterior  ribs.  Three  of  the  ribs  on  the  right  side  show  a  well- 
defined  angle,  while  none  of  those  on  the  left  side  exhibit  an  angle. 

In  so  far  as  our  present  knowledge  extends,  the  first  pair  of  ribs  in  the  Mysticeti 
are  relatively  short  and  noticeably  expanded  at  their  distal  extremities.  From  this 
peculiarity,  it  may  be  inferred  that  the  first  rib  is  not  represented  on  either  side.  In 
regard  to  length,  the  first  rib  shown  on  the  left  side,  in  comparison  to  the  following 
ribs,  fulfills  the  requirements  for  the  second  of  the  series.  The  proximal  end  of  this 
rib  is  concealed  by  the  matrix.  The  tubercula  of  the  two  ribs  that  overlie  the  above- 
mentioned  rib  are  exposed,  but  the  capitula  are  buried  in  the  matrix.  The  shafts  of 
all  the  foregoing  ribs  are  rather  slender  and  the  curvature  regular.  Turning  to  the  rib 
touching  the  fourth  dorsal  which  appears  to  be  the  seventh  rib,  it  will  be  observed  that 
the  neck  is  more  elongated  than  the  others  on  the  left  side,  while  the  curvature  is 


50  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


reduced.  This  is  the  longest  rib  preserved.  Since  this  rib  measures  920  mm.  in  length 
and  the  second  580  mm.,  it  is  evident  that  the  ribs  rapidly  increase  in  length  from  the 
second  to  the  rib  which  appears  to  be  the  seventh.  The  convex  external  curvature  of 
the  ribs  on  the  left  side  is  rather  regular,  and  this  curvature  is  more  pronounced  in  the 
rib  which  touches  the  fifth  dorsal  than  in  any  of  the  preceding  or  following  ribs.  All 
of  the  extremities  of  the  ribs  on  the  left  side  are  roughened  for  the  attachment  of  liga¬ 
ments.  The  capitula  of  2  of  the  ribs  on  the  right  side  are  borne  upon  long  necks; 
they  may  be  the  fifth  and  sixth  ribs.  Beyond  this  point,  the  identification  of  those 
that  remain  is  rather  uncertain;  one  of  these  ribs  is  single  headed  and  may  represent 
the  tenth  rib  on  the  right  side.  The  shafts  of  the  anterior  ribs  are  noticeably  flattened 
while  those  that  follow  tend  to  become  narrower  and  thicker. 

Plesiocetus  occidentalis,  new  species. 

Type  specimen. — Cat.  No.  M.1551;  Poratype,  Cat.  No.  M.1350,  Museum  of  Palaeon¬ 
tology,  University  of  California.  The  type  consists  of  an  imperfect  weathered  skull; 
the  rostrum,  supraorbital  and  zygomatic  processes,  periotics,  tympanies,  as  well  as 
some  of  the  bones  bounding  the  nasal  passages  are  missing.  The  skull  of  the  paratype  is 
also  incomplete  and,  although  greatly  eroded,  supplies  some  additional  structural  details. 

Type  locality. — No  record  of  the  accession  of  these  specimens  can  be  found  in  the 
museum  catalogues.  The  donor  and  occurrence  are  unknown. 

Horizon. — The  matrix  which  has  formed  the  natural  brain  cast  in  each  of  these 
skulls  is  a  hard  fine-grained  magnesian  limestone  or  dolomite  and  in  lithologic  appear¬ 
ance  agrees  with  certain  limestones  in  the  Monterey  formation.  Mr.  W.  F.  Foshag, 
of  the  United  States  National  Museum,  has  made  a  laboratory  examination  of  these 
natural  braincasts  and  reports  that  the  dolomite  in  skull  Cat.  No.  1350  is  more  siliceous 
than  that  of  Cat.  No.  1551.  Mysticetes  with  this  type  of  skull  had  a  rather  wide¬ 
spread  distribution  during  the  latter  part  of  the  Miocene  period;  Upper  Miocene, 
probably  Tortonian  or  later. 

As  mentioned  in  the  introductory  remarks,  the  degree  of  likeness  between  these 
skulls  cranially  is  so  marked  that  they  appear  to  be  conspecific.  Despite  certain 
structural  peculiarities  which  appear  in  the  illustrations  herewith  given,  the  size  and 
relations  of  the  elements  are  in  close  agreement  and  it  is  believed  that  whatever  differ¬ 
ences  are  exhibited  may  be  explained  on  the  basis  of  different  degrees  of  wear.  These 
skulls,  both  in  the  architecture  of  the  basicranium  and  in  the  form  of  the  temporal 
fossae,  bear  some  resemblance  to  the  skull  described  by  Strobel 1  from  the  Lowrer 
Pliocene  of  Cortandone,  Italy,  as  Cetotherium  gastaldii,  but  are  distinguished  from  the 
latter  by  sloping  supraorbital  processes  and  a  narrower  intertemporal  region.  In 
some  respects  they  agree  with  the  incomplete  skull  obtained  from  the  upper  sediment¬ 
ary  deposits  on  the  Cape  of  Espichel  beyond  the  Tejo  River  at  the  site  of  Adica  about 
4  leagues  from  Lisbon,  Portugal,  and  described  by  Van  Beneden 2  as  Cetotherium 
vandelli.  If  the  illustrations  used  by  Vandelli,  Van  Beneden,  and  Brandt  are  accurate, 
the  skull  from  Portugal  presents  some  unusual  features  for  a  cetothere.  The  outer 
margin  of  the  maxilla  may  be  incomplete  which  may  account  for  the  remarkable 
constriction  of  the  rostrum  anteriorly,  and  likewise  the  peculiar  appearance  of  the 
interorbital  and  intertemporal  regions  on  the  right  side  may  require  a  similar  explanation. 

In  order  to  demonstrate  the  validity  of  the  various  species  which  have  been  proposed 
it  will  be  necessary  to  show  differences  between  corresponding  structures.  Such 
comparisons,  unfortunately,  can  not  be  made  from  the  material  which  has  been  de¬ 
scribed  and  figured.  Unless  future  discoveries  or  undescribed  specimens  supply  such 

1  P.  Strobel,  Notizie  preliminari  zu  le  Balenoptere  fossili  subapennine  del  Museo  Parmense, 
Boll.  R.  Com.  Geol.  d’ltalia,  Roma,  vol.  6,  Nos.  5-6,  p.  136,  1875;  A.  Portis,  Catalogo  descrittivo 
dei  Talassoterii  rinvenuti  nei  terreni  Terziarii  del  Piemonte  e  della  Liguria,  Mem.  Reale  Accad. 
Sci.  di  Torino,  ser.  2,  vol.  37,  p.  17,  pi.  1,  figs.  3-5,  1885. 

*  P.  J.  Van  Beneden  and  P.  Gervais,  Osteographie  des  Cetaces  vivants  et  fossiles,  Paris,  pp. 
273-274,  Atlas,  pi.  17,  fig.  8,  1872  [Based  upon:  A.  A.  Vandelli,  Hist,  et  Mem.  Acad.  Real.  d.  Sci. 
de  Lisboa,  vol.  11,  pt.  1,  pp.  290,  304,  pi.  4,  figs.  1-12,  1831  J. 


Fossil  Cetotheres. 


51 


data,  the  relationships  of  many  of  these  forms  will  remain  unsettled.  Certain  struc¬ 
tures  have  been  considered  by  those  interested  in  this  subject  as  being  more  important 
than  others.  Of  these,  the  peculiarities  of  the  supraorbital  and  zygomatic  processes, 
the  contour  of  the  temporal  fossa,  and  the  size  and  shape  of  the  supraoccipital  shield 
are  thought  to  be  especially  diagnostic.  Certain  portions  of  the  skull  are  preserved 
more  frequently  than  others  and  in  consequence  many  species  have  been  based  upon 
variations  in  structures  which  may  or  may  not  be  of  specific  importance.  In  view  of 
the  present  inadequate  knowledge  of  the  structural  peculiarities  of  the  skulls  and 
skeletons  of  these  cetotheres  and  the  imperfect  preservation  of  the  parts  which  are 
known,  it  is  not  possible  at  the  present  time  to  attempt  a  revision  of  the  species. 

There  is  a  strong  possibility  that  one  or  more  genera  of  cetaceans  allied  to  Plesiocetus 
are  now  included  among  the  species  which  have  been  referred  to  Cetotherium.  That 
these  species  are  not  all  congeneric  is  borne  out  to  some  extent  by  differences  observable 
in  the  ear  bones.  Unfortunately,  the  periotic  and  tympanies  are  not  known  for  many 
of  the  described  species,  or  at  least  they  have  not  been  figured.  Brandt1  has  figured 
the  periotic  and  tympanic  of  Cetotherium  rathkii  and  unless  there  was  a  wider  range  of 
variation  among  these  Miocene  cetotheres  than  may  be  observed  between  species  of 
the  same  genus  in  case  of  living  mysticetaceans,  which  is  extremely  unlikely,  all 
species  of  the  genus  Cetotherium  should  possess  periotics  of  the  same  general  type. 
The  structural  peculiarities  of  the  periotic  in  the  type  skull  of  Cetotherium  megalophy- 
sum  Cope  do  not  correspond  with  those  of  the  periotic  of  Cetotherium  rathkii  figured  by 
Brandt,  nor  do  they  fall  within  the  range  of  specific  variation  as  understood  by  the 
writer.  The  skull  and  periotic  of  Cetotherium  megalophysum  does  exhibit  a  remarkable 
resemblance  to  that  of  Plesiocetus  hupschii  Van  Beneden.2 3 

In  order  to  clarify  the  discussion  which  follows,  the  species  hupschii  3  is  here  desig¬ 
nated  as  the  type  of  the  genus  Plesiocetus.  Furthermore  it  seems  advisable  to  change  the 
generic  allocation  of  Cetotherium  megalophysum  Cope,  and  as  it  possesses  all  the  diagnostic 
characters  of  Plesiocetus,  it  will  be  referred  to  as  Plesiocetus  megalophysum  (Cope). 

r 

Skulls. 

DORSAL  VIEW. 

On  account  of  the  loss  of  the  supraorbital  processes  on  one  skull  and  their  imperfect 
preservation  on  the  other,  critical  comparison  of  these  structures  with  other  species  is 
impossible.  The  zygomatic  processes  are  also  missing  on  both  of  these  skulls  and  there 
is  some  uncertainty  about  the  original  shape  of  the  supraoccipital  shield.  In  certain 
important  details,  these  two  skulls  differ  from  all  previously  figured  species,  and  in 
most  respects  they  appear  to  resemble  Plesiocetus  megalophysum  (Cope)  4  more 
closely  than  Cetotherium  rathkii  Brandt  or  Cetotherium  vandelli  Van  Beneden.  The 
supraorbital  processes  of  the  frontals  are  unusually  broad  at  the  base  and  slope  gradu¬ 
ally  downward  from  the  interorbital  region.  They  also  differ  from  Cetotherium  fur- 
longi  in  the  relative  breadths  of  the  supraorbital  processes  at  the  base,  in  the  position 
of  the  nasals,  in  the  curvature  of  the  posterior  margins  of  the  temporal  fossae,  and  in 
the  breadth  of  the  intertemporal  region. 

Inasmuch  as  considerable  importance  has  been  attributed  to  the  forward  thrust  of 
the  supraoccipital  shield,  it  is  unfortunate  that  this  structure  is  so  poorfy  preserved  on 
both  skulls.  Very  little  of  the  original  surfaces  of  the  bones  comprising  the  dorsal 
aspect  of  either  skull  is  preserved,  and  on  one  skull  (Cat.  No.  1551)  a  natural  braincast 
is  exposed.  On  the  other  skull  (text-fig.  8),  the  contour  of  the  supraoccipital  shield 

1  J.  F.  Brandt,  Untersuchungen  ueber  die  fossilen  und  subfossilen  Cetaceen  Europa’s,  Mem. 
Acad.  Imp.  Sci.  de  St.  Petersbourg,  ser.  7,  vol.  20,  No.  1,  pp.  74,  79-80,  pi.  3,  figs.  1-5,  1873. 

2  P.  J.  Van  Beneden  and  P.  Gervais,  Ost6ographie  des  Cetaces  vivants  et  fossiles,  Paris,  Atlas, 
pi.  16,  fig.  17,  1872-1880. 

3  P.  J.  Van  Beneden,  Bull,  Acad.  Roy.  Sci.  de  Belgique,  ser.  2,  tome  8,  No.  11,  p.  140,  1859. 

*  E.  D.  Cope,  Fourth  contribution  to  the  marine  fauna  of  the  Miocene  period  of  the  United 
States,  Proc.  Amer.  Philos,  Soc.  Philadelphia,  vol,  34,  No.  147,  pp.  146-148,  May  29,  1895;  op. 
cit.,  vol.  35.  No.  151,  pi.  11,  fig.  3,  August  13,  1896. 


52  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


may  be  traced,  although  the  cranium  is  badly  weathered  and  on  each  side  of  the 
median  line  a  small  portion  of  a  natural  cast  of  the  lobe  of  the  cerebrum  is  exposed. 
As  a  whole  the  supraoccipital  appears  to  slope  forward  and  become  narrower  toward  the 
vertex.  The  exact  position  of  the  apex  of  the  supraoccipital  shield  is  uncertain.  The 
extremities  of  the  exoccipitals  have  been  destroyed  on  both  skulls.  One  skull  (text-fig. 
7)  shows  the  curvature  of  the  wing-like  portion  of  the  exoccipital  and  the  other  (text- 
fig.  8)  the  proportions  and  outlines  of  the  occipital  condyles.  From  a  posterior  view, 
the  condyles  appear  semielliptical  in  outline,  considerably  broader  above  the  middle 
than  at  the  base.  The  articular  surfaces  are  slightly  convex,  more  or  less  flattened, 
and  set  off  from  the  exoccipitals  by  shallow  concavities.  The  occipital  condyles  of 
this  cetacean  bear  a  closer  resemblance  to  those  of  Plesiocetus  megalophysum  than  to 
any  of  the  other  forms  from  the  Atlantic  Tertiary  deposits  described  by  Cope.  The 
opening  for  the  foramen  magnum  is  almost  circular. 


Fig.  7 — Dorsal  view  of  type  skull  of  Plesiocetus  occidentalis.  Cat.  No.  1551,  Palaeont.  Mus. 

Univ.  Calif.  C.,  condyle;  Ex.  oc.,  exoccipital;  Fr.,  frontal;  Na.,  nasal;  Pa.,  parietal; 
Pmx.,  premaxilla;  S.  oc.,  supraoccipital;  Sq.,  squamosal. 


The  form  and  dimensions  of  the  bones  comprising  the  rostrum  are  unknown.  The 
sutures  on  the  frontals  for  the  reception  of  the  ascending  processes  of  the  premaxillae 
and  for  the  postero-mesial  processes  of  the  maxillae  are  deep  and  well  defined  on  both 
of  the  skulls.  More  evidence  of  erosion  in  the  intertemporal  region  is  shown  on  one 
skull  (text-fig.  7)  than  on  the  other  and  in  addition  the  anterior  projections  of  the 
frontals  and  the  distal  ends  of  the  nasals  have  been  worn  off.  The  nasals  are  in  place 
on  both  of  these  skulls,  although  their  dorsal  surfaces  are  considerably  eroded.  As  in 
many  of  the  living  balaenopterine  whales,  the  nasals  are  relatively  narrow,  but  rather 
deep.  They  are  wedged  in  between  the  anterior  projections  of  the  frontals,  and  firmly 
sutured  at  their  bases.  The  nasals  on  skull  Cat.  No.  1350  are  approximately  complete, 
though  it  is  possible  that  short  sections  of  their  anterior  extremities  are  missing. 


Fossil  Cetotheres. 


53 


The  frontals  form  the  rostral  wall  of  the  cranial  cavity  and  their  lateral  projections, 
the  supraorbital  processes,  roof  over  the  orbit.  They  are  excluded  from  the  vertex  by 
the  parietals  which  meet  mesially  in  the  intertemporal  region. 

From  a  lateral  view,  the  parietal  is  seen  to  be  rather  broadly  expanded,  somewhat 
fan-shaped  in  general  contour,  with  its  greatest  diameter  along  the  superior  margin. 
It  bounds  the  temporal  fossa  internally  and  descends  abruptly  from  the  upper  to  the 
lower  margin.  The  most  obvious  difference  between  the  skull  of  Plesiocetus  megal- 
ophysum  and  these  skulls  from  California  is  the  swollen  appearance  of  the  side  of  the 
braincase  in  the  former.  This  swelling  is  bisected  by  the  more  or  less  horizontal  suture 
between  the  parietal  and  squamosal.  Furthermore,  in  the  skull  of  Plesiocetus  megal- 
ophysum  the  parietals  do  not  overspread  the  frontals  to  any  marked  extent  and  termi¬ 
nate  at  the  level  of  the  posterior  margins  of  the  supraorbital  processes.  The  superior 


Fig.  8. — Dorsal  view  of  paratype  skull  of  Plesiocetus  occidentalis.  Cat.  No.  1350,  Palaeont. 

Mus.,  Univ.  Calif.  C.,  condyle;  Ex.  oc.,  exoccipital;  Fr.,  frontal;  Na.,  nasal;  Pa. 
parietal;  Pmx.  premaxilla;  S.  oc.,  supraoccipital;  Sq.,  squamosal. 


margins  of  the  parietals  on  the  skulls  from  California  are  worn  down  below  the  level  of 
the  supraoccipital  suture.  In  all  three  of  these  skulls,  the  parietal  is  sutured  to  the 
supraoccipital  posteriorly,  the  squamosal,  alisphenoid,  and  pterygoid  interiorly,  and 
the  frontal  anteriorly.  The  eroded  surfaces  of  these  California  skulls  show  that  the 
parietals  overspread  the  frontals  in  the  interorbital  region  to  a  point  about  halfway 
between  the  extremities  of  the  nasals  and  the  posterior  margins  of  the  supraorbital 
processes.  In  the  temporal  fossa,  the  pterygoid  lies  below  the  parietal  and  is  in  contact 
posteriorly  with  the  squamosal.  Between  them  appears  the  extremity  of  the  narrow 
wedge-like  alisphenoid. 


54  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast .  . 


as  the  anterior  margins  of  the  pterygoid  fossae.  The  pterygoids  on  the  skull  of  Ceto- 
therium  rathkii,  apparently,  have  not  developed  hamular  processes.  In  the  temporal 
fossa  (text-fig.  9),  the  pterygoid  is  suturally  united  with  the  squamosal,  and  anteriorly 
forms  the  posterior  wall  of  the  optic  canal.  The  structure  of  the  pterygoid  fossa 
resembles  that  of  Parietobalaena  palmeri. 2  It  should  be  noted  that  the  falciform 
processes  of  the  squamosals  have  been  eroded  away  on  both  skulls.  The  bell-like 
contour  of  the  tympano-periotic  recess  is  a  characteristic  feature  of  this  cetothere. 
In  a  better-preserved  skull,  the  inferior  outlines  of  this  recess  would  appear  somewhat 
different.  A  postero-internal  process  of  the  squamosal  usually  projects  into  this  recess 

1  J.  F.  Brandt,  op.  cit.,  pi.  1,  fig.  2;  pi.  2,  fig.  2,  1873. 

2  R.  Kellogg,  Description  of  a  new  genus  and  species  of  whalebone  whale  from  the  Calvert 
Cliffs,  Maryland,  Proc.  U.  S.  Nat.  Mus.,  vol.  63,  art.  15,  Publ.  2483,  pi.  4,  February  5,  1924. 


VENTRAL  VIEW. 

On  each  side  the  basisphenoid  is  overridden  by  the  pterygoid  (text-fig.  9)  and  the 
narrow  extremity  of  the  latter  abuts  against  the  anterior  face  of  the  lateral  protuber¬ 
ance  on  the  basioccipital.  The  ventral  face  of  the  other  skull  (text-fig.  10)  has  suffered 
to  a  great  extent  from  erosion,  and  all  of  the  left  pterygoid  as  well  as  the  extremity  of 
the  right  pterygoid  are  missing.  These  pterygoid  bones  bound  the  medial  region  of 
the  basicranium  on  each  side  and  together  with  the  vomer  contribute  the  upper 
posterior  boundary  of  each  nasal  passage.  No  remnant  of  a  hamular  process  is  present 
on  either  of  these  skulls.  By  referring  to  the  figures  given  by  Brandt1  for  Ceto- 
therium  rathkii  one  can  interpret  most  of  the  elements  which  are  exposed  on  these  skulls 
from  California.  According  to  his  illustrations,  the  palatines  extend  backward  as  far 


Fig.  9. — Ventral  view  of  type  skull  of  Plesiocetus  occidentalis.  Cat.  No.  1551,  Palaeont.  Mus., 
Univ.  Calif.  Ant.  pr.,  anterior  process  of  periotic;  Ap.  per.,  apophysis  or  posterior 
process  of  periotic;  Bo.,  basioccipital;  Bs.,  basisphenoid;  Ex.  oc.,  exoccipital;  Fr., 
frontal;  J.  A.  C.,  jugulo-acoustic  canal;  L.  pro.,  lateral  protuberance  on  basioccipital; 
Na.,  nasal;  Prs.,  presphenoid;  Pt.,  pterygoid,  Sq.,  squamosal. 


Fossil  Cetotheres. 


55 


below  the  periotic,  and  in  front  the  falciform  process  extends  across  to  meet  the  horizon¬ 
tally  expanded  pterygoid.  This  recess  is  bounded  by  the  squamosal  externally,  the 
exoccipital  posteriorly,  the  basioccipital  and  basisphenoid  internally,  and  by  the 
alisphenoid  and  the  overlying  pterygoid  anteriorly.  As  a  result  of  weathering,  the 
pterygoid  has  been  entirely  destroyed  on  one  skull  (text-fig.  10)  and  the  ventral  face 
of  the  alisphenoid  is  exposed  to  view.  The  zygomatic  processes  of  both  skulls  are 
missing,  and  the  cranial  portions  of  the  squamosals  are  also  damaged.  With  regard 
to  the  squamosal,  it  will  be  noted  that  it  is  a  rather  large  bone,  firmly  fixed  to  the  side 
of  the  braincase  and  internally  forms  part  of  the  wall  of  the  cranial  cavity. 


Fig.  10. — Ventral  view  of  paratype  skull  of  Plesiocetus  occidentalis.  Cat.  No.  1350.  Palaeont, 
Mus.,  Univ.  Calif.  Bo.,  basioccipital;  Bs.,  basisphenoid;  Ex.  oc.,  exoccipital;  Ft., 
frontal;  J.  A.  C.,  juguloacoustic  canal;  Max.,  maxilla;  Op.  C.,  optic  canal;  Prs., 
presphenoid;  Pt.,  pterygoid;  S.  or.  pr.,  supraorbital  process  of  frontal;  Sq., 
squamosal;  Vo.,  vomer. 

In  one  of  these  skulls  (text-fig.  9),  portions  of  the  apophyses  of  both  periotics  are 
preserved.  The  apophysis  of  the  periotic  is  lodged  in  a  narrow  trough  on  the  squamo¬ 
sal  between  the  exoccipital  suture  and  the  usual  position  of  the  transverse  groove  for 
the  external  auditory  meatus.  The  surface  of  the  squamosal  in  this  region  has  been 
worn  to  such  an  extent  that  the  groove  for  the  meatus  has  been  obliterated.  On  the 
other  skull  (text-fig.  10),  the  effect  of  erosion  is  more  noticeable;  the  exposed  surfaces 
of  the  exoccipital  and  squamosal  are  worn  down  below  the  level  of  the  trough  for  the 
apophysis  of  the  periotic.  The  position  and  course  of  the  jugulo-acoustic  canal  is 
fairly  well  marked  on  both  skulls.  This  canal  originates  within  the  cranial  cavity, 
follows  down  the  external  surface  of  the  basioccipital,  appears  on  the  ventral  face  of 
the  basicranium  in  the  angle  formed  by  the  exoccipital  and  the  basioccipital,  and  crosses 
the  former  in  an  oblique  direction  to  its  posterior  margin. 

The  basioccipital  is  considerably  wider  than  long,  with  ventral  surface  concave  from 
side  to  side.  The  suture  between  the  basioccipital  and  basisphenoid  is  not  well  defined, 


56  Tertiary*  History  of  Pelagic  Mammals  of  Pacific  Coast. 


but  appears  to  be  in  front  of  the  lateral  protuberance.  On  the  right  side  of  one  skull 
(text-fig.  9)  the  lateral  protuberance  is  practically  complete;  the  internal  face  is 
obliquely  truncated,  while  the  external  is  vertically  truncated.  The  occipital  condyles 
are  low  and  flattened,  and  apparently  do  not  project  backward  beyond  the  plane  of  the 
exoccipitals. 

Further  mention  must  be  made  of  the  broad  basisphenoid,  which  in  a  perfect  skull 
may  be  largely  concealed  by  the  horizontally  expanded  vomer.  The  anterior  margin 
of  this  bone  is  concave  and  it  is  separated  from  the  presphenoid  by  an  open  transverse 
fissure.  The  presphenoid  is  emarginate  posteriorly,  with  a  short  mesial  process,  sub- 
cylindrical  in  cross-section,  and  tapering  anteriorly.  Normally,  the  presphenoid  rests 
in  the  trough  of  the  vomer,  and  is  not  visible  from  a  ventral  view.  On  one  of  these 
skulls  (text-fig.  10),  portions  of  the  lateral  walls  of  the  vomerine  trough  are  preserved. 
The  vomer  also  conceals  the  above-mentioned  transverse  fissure,  and  its  horizontally 
expanded  wings  meet  the  vaginal  plates  of  the  pterygoids  along  its  lateral  margins. 

Practically  the  entire  course  of  the  optic  canal  is  shown  on  one  of  these  skulls  (text- 
fig.  10).  Near  its  origin,  this  canal  is  bounded  by  the  frontal  anteriorly,  presumably 
by  the  palatine  interiorly,  and  by  the  pterygoid  and  alisphenoid  posteriorly.  This 
canal  is  very  narrow  in  comparison  to  the  breadth  of  the  supraorbital  process  and  fol¬ 
lows  the  posterior  margin  of  the  latter  on  the  proximal  one-half  at  least  of  its  outward 
course.  The  optic  canal  is  thus  exposed  interiorly,  although  there  is  a  noticeable 
overrolling  of  the  anterior  margin. 

From  a  ventral  view  (text-fig.  10),  the  supraorbital  processes  appear  to  be  rather  - 
broad  at  the  base.  The  ventral  surface  of  the  base  of  the  left  supraorbital  process  is 
flattened  and  no  doubt  was  overspread  by  the  orbital  plate  of  the  maxilla.  One  of  the 
most  diagnositic  features  of  a  mysticete  skull  is  the  shape  of  the  temporal  fossa. 
Since  the  zygomatic  processes  and  the  extremities  of  the  supraorbital  processes  are 
missing  on  both  of  these  skulls,  a  structural  feature  of  considerable  importance  is  left 
unsettled.  The  narrowness  of  this  fossa  at  the  base  (text-fig.  10),  the  curvature  of  the 
posterior  margin  of  the  supraorbital  process,  and  the  anterior  border  of  the  squamosal 
impart  a  characteristic  contour  to  the  internal  portion  of  the  fossa,  and  in  this  respect 
it  agrees  rather  closely  with  Balaenoptera  gastaldii. 


Measurements  of  the  skulls. 


Cat  No. 
M.  1350. 

Cat.  No. 
M.  1551. 

Least  breadth  of  braincase  in  intertemporal  region . 

mm. 

177 

mm. 

172.5 

Distance  from  base  of  right  nasal  to  right  occipital  condyle . 

375 

387 

Length  of  right  nasal . 

110 

85 

Breadth  of  right  nasal  at  base . 

15 

14 

Breadth  of  right  nasal  at  extremity . . . 

24 

22.5 

Depth  of  right  nasal  at  extremity . 

X 

46 

Height  of  foramen  magnum . . . 

60 

x 

Height  of  left  condyle . 

98 

X 

Greatest  breadth  of  left  condyle . 

61 

X 

Breadth  across  combined  condyles . 

157 

X 

Length  of  basioccipital  along  median  line . 

86.5 

94 

Breadth  of  basioccipital  between  jugulo-acoustic  canals . 

141 

150 

Length  of  right  tympano-periotic  recess . 

81 

x 

Breadth  of  right  tympano-periotic  recess . 

91 

88 

Length  of  basisphenoid . 

91.5 

94 

Least  breadth  of  supraorbital  process,  ventral  side . 

248 

X 

Distance  from  condylar  notch  to  anterior  margin  of  basisphenoid . 

178 

188 

Distance  from  right  condyle  to  tip  of  right  nasal . 

458 

449 

Vertical  depth  of  skull  in  interorbital  region  (presphenoid  to  frontal).  .  . 
Vertical  depth  of  skull  in  occipital  region  (basisphenoid  to  apex  occipital 
shield)  estimated . 

X 

170  + 

180 

160  + 

III.  A  NEW  FOSSIL  SIRENIAN  FROM  SANTA  BARBARA 

COUNTY,  CALIFORNIA. 

An  unusually  large  sirenian  recently  submitted  to  the  writer  for 
study  by  Dr.  David  Starr  Jordan  is  of  special  interest  on  account  of 
the  fact  that  it  constitutes  the  first  reported  occurrence  on  the 
Pacific  Coast  of  North  America  of  a  representative  of  the  suborder 
Trichechiformes.  The  skull  was  covered  with  an  encrustation  of  soda 
and  compact  diatomaceous  shale;  the  ribs  and  dorsal  vertebrae  were 
embedded  in  a  laminated  opal.  Some  difficulty  was  encountered  in 
preparaing  the  material,  for  the  matrix  clings  very  closely  to  the  bones. 

Aside  from  the  sirenians  now  living,  the  skulls  either  in  whole  or  in 
part  are  known  for  one  extinct  and  at  least  12  Tertiary  genera.  One 
of  these  genera  appears  to  have  had  a  rather  wide  geographic  range 
during  the  Miocene  and  its  geologic  range  as  now  understood  extends 
from  the  Lower  to  the  Upper  Miocene.  This  is  the  genus  Metaxy- 
therium,  a  widely  spread,  migratory  sirenian,  for  specimens  referable 
to  this  genus  have  been  found  not  only  in  Europe,  but  also  in  Florida, 
and  with  this  discovery  in  California  as  well.  This  sirenian  no  doubt 
was  fairly  abundant  in  many  parts  of  the  world  during  that  period, 
frequenting  bays  and  the  mouths  of  rivers,  and  feeding  upon  the 
succulent  aquatic  vegetation  of  that  time. 

The  molariform  series  of  Metaxytherium  consists  of  four  or  five 
teeth.  Turning  to  this  fossil  skull,  it  is  to  be  regretted  that  the 
rostrum  and  palate  are  missing.  The  fractures  are  fresh  and  indicate 
that  portions  at  least  of  these  structures  were  present  when  the  skull 
was  first  discovered  in  the  Celite  quarry.  The  specimen  was  found 
by  workmen  who  were  unfamiliar  with  the  importance  of  such 
objects,  and  the  teeth,  if  present,  were  not  saved  when  the  specimen 
was  removed  from  its  resting  place.  Disregarding  for  the  present 
the  possibility  that  this  sirenian  may  have  been  endentulous,  it  is 
sufficient  to  state  that  in  all  other  features  the  skull  is  in  entire 
agreement  with  skulls  found  in  France  which  have  been  referred  to 
Metaxytherium.  The  Miocene  sirenians  of  the  genus  Metaxytherium 
differ  from  the  extinct  Hydrodamalis  in  their  method  of  feeding  in 
that  they  masticated  their  food,  thus  requiring  molariform  teeth, 
the  functional  use  of  the  temporal  and  masseteric  muscles,  the 
enlargement  of  the  coronoid  process  of  the  mandible,  and  the  develop¬ 
ment  of  temporal  ridges  on  the  braincase.  The  surfaces  of  the  molari¬ 
form  teeth  are  not  so  well  adapted  for  grinding  as  some  of  the 
terrestrial  ungulates,  but  they  are  suited  for  cutting  aquatic  vege- 

57 


58  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


tation.  The  articulation  of  the  jaw  is  so  as  to  limit  the  process  of 
mastication  and  would  seem  to  indicate  that  the  breaking  up  of  the 
vegetable  tissues  was  accomplished  by  up  and  down  movements  of 
the  jaws  rather  than  by  any  lateral  or  side  to  side  movements.  There 
may  have  been  some  movement  in  a  fore-and-aft  direction  or  even  a 
slight  rotary  motion  which  would  account  for  the  worn  teeth  which 
have  been  discovered  in  Europe.  Differences  in  the  type  of  vegeta¬ 
tion  sought  for  as  food  would  unquestionably  be  reflected  in  the 
degree  of  attrition  exhibited  by  the  molariform  series  at  any  given 
age.  Judging  from  the  worn  molars  of  some  of  the  species  of  Metaxy - 
therium  one  would  be  led  to  conclude  that  their  food  consisted  of 
aquatic  vegetation  which  contained  a  certain  amount  of  coarse 
fibers.  Some  of  the  Eocene  sirenians  possessed  the  typical  Eutherian 
dentition.  Since  the  trend  of  evolution  as  exhibited  by  the  fossil 
species  has  been  toward  the  loss  of  the  anterior  teeth  and  reduction 
of  the  molariform  series  from  in  front  and  from  behind.  This  process 
reached  its  culmination  in  the  edentulous  Hydrodamalis  stelleri. 

The  skeletons  of  many  of  the  Tertiary  sirenians  have  never  been 
discovered;  composite  skeletons  have  been  assembled  for  some  and 
in  a  few  instances  fairly  complete  specimens  have  been  found. 
Deperet’s  observations  would  indicate  that  sufficient  material 
has  been  assembled  to  furnish  the  size  of  at  least  four  of  the  European 
sirenians,  the  total  lengths  of  which  he  estimates  as  follows:  the 
Stampian  Halitherium  schinzi,  8  feet  5  inches;  the  Vindobonian 
Metaxytherium  cuvieri ,  10  feet  5  inches;  the  Pontian  Miosiren  kocki, 
11  feet  6  inches;  and  the  Plaisancian  Felsinotherium  serresii,  8  feet. 
The  sirenian  found  in  California  appears  to  have  been  considerably 
larger  than  any  of  the  above  mentioned  species.  A  reasonable 
estimate  of  the  total  length  of  the  skeleton  would  be  about  15  feet. 
Estimates  for  the  skeleton  of  the  Holocene  sirenian  Hydrodamalis 
stelleri,  which  became  extinct  about  1768  according  to  Stejneger, 
vary  considerably,  the  lengths  given  ranging  from  26  to  34  feet. 

Turning  to  Miosiren  kocki  from  the  Upper  Miocene  of  Belgium,  the 
detailed  description  of  which  has  not  been  published  as  yet  by  Dollo, 
one  may  infer  from  published  statements  that  it  does  not  resemble  the 
sirenian  found  in  California.  The  enlargement  of  the  posterior 
portion  of  the  braincase,  the  reduction  or  absence  of  temporal  crests, 
and  the  rounded  appearance  of  the  top  of  the  cranium  of  Miosiren 
kocki  suggest  a  relationship  with  Hydrodamalis  rather  than  with 
Metaxytherium.  As  regards  the  contour  of  the  cranium  and  devel¬ 
opment  of  the  temporal  crests,  the  lengthening  of  the  pre-maxilla, 
the  outlines  of  the  mesorostral  fossa,  and  the  shape  of  the  mandible, 
the  Pliocene  Felsinotherium  resembles  the  Miocene  Metaxytherium. 
In  view  of  this  resemblance,  comparisons  with  Metaxytherium  and 
Felsinotherium  will  be  made  in  the  following  description. 


A  Fossil  Sirenian. 


59 


During  the  latter  part  of  the  Miocene  period,  sirenians  frequented 
the  Atlantic  Coast  of  North  America  at  least  as  far  north  as  the 
Chesapeake  Bay.  In  the  light  of  the  recorded  material  it  is  not 
possible  to  state  whether  or  not  the  genus  Metaxytherium  is  repre¬ 
sented  in  all  of  the  following  occurrences.  Case1  records  the  occur¬ 
rence  of  a  fused  radius  and  ulna,  and  a  rib  fragment  at  Fairhaven, 
Maryland,  in  the  Calvert  formation.  A  fifth  cervical  vertebra  from 
the  same  formation  has  been  discussed  by  William  Palmer,2  but  his 
view  that  it  was  redeposited  from  an  earlier,  possibly  Eocene,  forma¬ 
tion  does  not  appear  plausible.  A  fragment  of  a  premaxillary 
bone  with  a  tusk-like  incisor  in  place  from  the  phosphate  beds  of  the 
Wando  River,  northeast  of  Charleston,  South  Carolina,  in  1883  was 
described  by  Cope3 4  as  Dioplotherium  manigaulti.  According  to 
Cope,  two  pair  of  tusk-like  incisor  teeth  were  present  in  each  pre¬ 
maxilla,  whereas  only  one  pair  has  been  observed  in  Metaxytherium. 
This  interpretation  is  probably  incorrect.  The  type  specimen,  which 
was  loaned  to  the  writer  by  the  authorities  of  the  Charleston 
Museum,  agrees  in  all  essential  details  with  a  portion  of  the  rostrum 
of  another  individual  from  the  same  formation  in  the  collection  of 
Yale  University.  The  premaxilla  of  this  specimen  is  broken  off  near 
the  extremity.  A  single  large  tusk,  measuring  49.5  mm.  by  25.5  mm. 
in  cross-section,  is  present  in  the  premaxilla.  There  is  no  indication 
of  an  alveolus  for  a  second  incisor.  Therefore  until  this  animal  can 
be  shown  to  differ  from  Metaxytherium  it  seems  advisable  to  refer 
Cope’s  species  to  that  genus.  More  recently  remains  of  Metaxy¬ 
therium  floridanum 4  have  been  discovered  at  several  localities  in 
Florida  in  the  land-pebble  phosphate  deposits. 

Some  of  the  most  notable  anatomical  features  of  the  sirenian 
found  at  Lompoc  are  the  large  size  of  the  skull  and  vertebrae,  the 
position  of  the  nasal  bones,  the  structural  peculiarities  of  the  olfac¬ 
tory  bones,  and  the  type  of  brain  as  revealed  by  an  endocranial  cast. 

Metaxytherium  jordani,  new  species. 

Type  specimen. — Cat.  No.  10,  Museum,  Stanford  University.  The  material  includes 
an  incomplete  skull  lacking  the  rostrum,  zygomatic  arches,  and  basicranium,  as  well 
as  four  dorsal  vertebrae,  the  proximal  ends  of  two  ribs  and  fragments  of  four  others, 
and  one  metacarpal. 

Type  locality. — The  Celite  Company’s  No.  5  Quarry,  600  feet  north  from  north¬ 
west  corner  of  the  NE.  34  of  Section  22,  Township  6  North,  Range  34  West,  San 

1  E.  C.  Case,  Miocene  text.  Maryland  Geol.  Surv.,  Baltimore,  pp.  56-58;  Atlas,  pi.  26,  fig.  1. 
1904. 

1  W.  Palmer,  The  fossil  sea  cow  of  Maryland,  Science,  new  ser.,  vol.  45,  p.  334,  1917. 

*  E.  D.  Cope,  On  a  new  extinct  genus  of  Sirenia  from  South  Carolina.  Proc.  Acad.  Nat.  Sci. 
Philadelphia,  pp.  52-54,  1883;  The  extinct  Sirenia,  Amer.  Nat.,  vol.  24,  No.  284,  p.  698,  pi.  25, 
figs.  1-5,  1890. 

4  O.  P.  Hay,  Description  of  a  new  fossil  sea  cow  from  Florida,  Metaxytherium  floridanum, 
Proc.  U.  S.  Nat.  Mus.,  vol.  61,  Publ.  2438,  pp.  1-4,  pi.  1,  May  3,  1922;  G.  M.  Allen,  Additional 
remains  of  the  fossil  dugong  of  Florida,  Journ.  of  Mammalogy,  vol.  4,  No.  4,  pp.  231-239,  pi.  26, 
with  1  text  fig.,  Nov.  1923. 


60  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


Bernardino  Base  and  Meridian,  2.5  miles  south  and  east  of  Lompoc,  Santa  Barbara 
County,  California. 

Horizon. — This  specimen  was  first  discovered  by  workmen  quarrying  diatomaceous 
earth.  Mr.  Edward  B.  Starr,  superintendent  of  the  Celite  Products  Company,  com¬ 
municated  the  discovery  to  Dr.  David  Starr  Jordan  and  arrangements  were  completed 
for  Mr.  Eric  Knight  Jordan  to  visit  the  locality  in  May  1924,  and  collect  the  material 
for  Stanford  University.  This  deposit  of  diatomaceous  earth  has  a  total  thickness  of 
1,400  feet  near  Lompoc.  The  sirenian  remains  were  taken  from  a  stratum  within  300 
feet  of  the  top  of  the  deposit,  that  is  at  least  1,100  feet  above  the  base.  Sarmatian, 
or  Upper  Miocene. 

The  following  analysis  of  the  matrix  which  enveloped  the  vertebrae  and  ribs  has  been 
furnished  by  Mr.  Earl  V.  Shannon,  Assistant  Curator  of  Geology,  United  States 
National  Museum. 

“The  analysis  of  the  specimen  submitted  indicates  that  it  is  unquestionably  opal. 
This  is  probably  a  percolating  water  deposit.  The  banding  is  possibly  in  part  in¬ 
herited  from  the  parent  diatomaceous  earth  or,  more  probably,  is  diffusion  banding 
similar  to  that  characteristic  of  many  deposits  of  opal  or  agate.  The  variation  in  color 
is  due  more  to  varying  texture  than  to  differences  in  composition  and  is  similar  to  the 
variation  in  many  specimens  of  opalized  wood.  Under  the  microscope  the  material  is 
entirely  isotropic  with  the  exception  of  a  few  obscure  bands  of  feeble  birefringence  and 
a  chalceodonic  fibrous  structure.  The  average  index  of  refraction  is  about  1.440 
although  different  layers  vary  from  1.435  to  1.445.  A  partial  analysis  on  the  material 
gave  the  following  results: 

Per  cent 


Silica  (Si02) .  88.92 

Bases,  largely  Fe203. .  2.28 

Water .  8.80 


Total .  100.00 


“The  hardness  of  the  material  is  slightly  above  5.0;  luster  waxy;  and  fracture  im¬ 
perfectly  conchoidal.  This  evidence  conclusively  proves  that  the  material  is  not  a 
glassy  volcanic  rock.” 

Additional  information  regarding  the  deposits  of  diatomaceous  earth  just  south  of 
Lompoc  in  the  foothills  of  the  Santa  Ynez  Range,  east  of  the  canyon  of  San  Miguelito 
Creek,  will  be  found  in  a  report  by  Arnold  and  Anderson.1 

Skull. 

One  of  the  characteristic  features  of  a  sirenian  skull  is  the  position  and  shape  of  the 
fossa  formed  by  the  bones  bordering  upon  the  external  nasal  apertures.  Taken 
together,  the  nasal  passages  terminate  in  a  deep  meso-rostral  fossa  which  varies  in 
size  and  shape  in  the  several  forms  now  known.  In  one  Miocene  form,  Rytiodus 
capgrandi ,2  it  is  considerably  longer  than  wide;  in  others  there  is  a  more  evident  widen¬ 
ing  of  the  meso-rostral  fossa.  The  meso-rostral  fossa,  in  all  forms  thus  far  described, 
is  closed  anteriorly  by  the  approximation  of  the  premaxillae  and  extends  backward 
to  a  point  behind  the  orbits.  Practically  all  of  the  rostrum  of  the  fossil  sirenian  skull 
hereinafter  described  is  missing.  The  left  premaxilla  is  broken  off  at  a  point  corres¬ 
ponding  to  the  level  of  the  antorbital  notches.  A  small  fragment  of  the  left  maxilla  is 
applied  to  its  outer  border.  Hence  the  contour  of  the  anterior  portion  of  the  meso- 
rostral  fossa  of  this  skull  is  unknown.  Judging  from  the  relations  of  the  bones  which 

1  R.  Arnold  and  R.  Anderson,  Contributions  to  Economic  Geology  1906;  Diatomaceous 
deposits  of  northern  Santa  Barbara  County,  Cal.,  Bull.  No.  315,  U.  S.  Geol.  S'urv.,  p.  440.  1907. 

2  E.  Lartet,  Note  sur  deux  nouveaux  Sireniens  fossiles  des  terrains  tertiaires  du  basin  de  la 
Garonne,  Bull.  Soc.  Geol.  de  France,  Paris,  ser.  2,  tome  23,  pp.  673-686,  pi.  13,  1866;  E.  Del- 
fortrie,  Decouverte  d’un  Squelette  entier  de  Rytiodus  dans  le  falun  Aquitanien,  Actes  Soc. 
Linn,  de  Bordeaux,  ser.  4,  tome  4,  pp.  131-144,  pis.  5-8.  1880. 


A  Fossil  Sirenian. 


61 


bound  the  posterior  portion  of  this  fossa,  it  would  appear  that  it  bore  some  resemblance 
to  that  of  F elsinotherium  serresii.1 2 

In  the  sirenian  skulls  thus  far  described,  the  premaxillae  form  the  greater  part  of  the 
downwardly  directed  rostrum;  the  suture  between  these  bones  and  the  maxillae  may  be 
said  to  commence  near  the  posterior  border  of  the  incisive  foramina  and,  after  crossing 
the  alveolar  border,  runs  first  upward  and  backward,  then  nearly  backward  on  the  side 
of  the  rostrum,  terminating  at  the  level  of  the  anterior  border  of  the  postorbital  pro¬ 
cesses  of  the  frontals.  At  the  level  of  the  antorbital  notch,  the  facial  process  of  the 
premaxilla  is  deflected  obliquely  inward  in  this  Californian  sirenian  and  is  applied 
externally  to  the  postorbital  process  of  the  frontal,  with  its  extremity  terminating 
slightly  in  front  of  the  posterior  border  of  the  meso-rostral  fossa.  Here,  it  is  suturally 
united  with  the  nasal  and  interiorly  abuts  against  the  frontal,  thus  excluding  the  max¬ 
illa  from  any  share  in  the  superior  border  of  the  meso-rostral  fossa. 

As  will  be  seen  from  the  illustration  (pi.  10),  this  cranial  fragment  exhibits  a  general 
resemblance  to  the  corresponding  portion  of  the  skull  of  Hydrodamalis  stelleri.  In 
size,  the  specimen  agrees  very  closely  with  a  skull  (Cat.  No.  218,  326  U.  S.  Nat.  Mus.) 
of  Steller’s  sea-cow  from  Bering  Island.  Nevertheless,  it  is  very  unlikely  that  this 
sirenian  possesses  any  close  relationship  with  Hydrodamalis.  In  the  first  place,  the 
nasals  overspread  the  frontals  on  this  fossil  skull,  the  parietals  and  frontals  are  about 
equal  in  length  on  the  top  of  the  cranium,  but  the  olfactory  chamber  is  relatively  short. 
In  the  Hydrodamalis  skull,  the  nasals  are  applied  to  the  ventral  surfaces  of  the  frontals 
on  the  roof  and  sides  of  the  olfactory  chamber,  the  parietals  and  frontals  likewise  are 
about  equal  in  length  on  the  top  of  the  cranium,  but  the  olfactory  chamber  is  relatively 
long.  Secondly,  the  premaxillae  are  in  contact  with  the  nasals  in  both  sirenians. 
Furthermore,  the  facial  processes  of  the  premaxillae  retain  the  same  position  and  rela¬ 
tions  with  the  postorbital  processes  of  the  frontals  and  the  meso-rostral  fossa  in  both 
species.  Without  some  alteration  or  shifting  in  the  position  of  the  bones  involved, 
and  there  appears  to  be  no  such  possibility  in  the  types  under  consideration,  it  would 
appear  difficult  to  account  for  such  a  migration  of  the  nasal  bones,  Such  a  change  in 
the  position  of  the  nasal  bones  appears  unlikely,  especially  since  the  component  bones 
of  the  cranium  of  these  sirenians  are  essentially  the  same  both  in  size  and  in  position. 
To  postulate  the  hypothesis  that  the  edentulous  Hydrodamalis  is  a  derivative  of  this 
type  of  sirenian,  it  will  be  necessary  to  account  for  the  shifting  of  the  nasals  from  a 
position  on  top  of  the  frontals  to  one  immediately  below  and  within  the  olfactory 
chamber.  Following  such  a  line  of  reasoning  it  would  be  necessary  to  assume  that 
inasmuch  as  the  nasal  was  already  mortised  into  the  dorsal  surface  of  the  frontal  in 
these  Miocene  sirenian  skulls,  in  the  course  of  time  the  thin  edges  of  the  frontal  would 
gradually  overspread  the  nasal  until  it  was  no  longer  visible  on  the  dorsal  surface  of  the 
cranium.  To  account  for  its  present  condition  within  the  olfactory  chamber  in  the 
Hydrodamalis  skull  it  would  be  necessary  to  assume  further  that  the  portion  of  the 
frontal  which  underlies  the  nasal  in  Metaxytherium  or  its  allies  was  correspondingly 
reduced  and  finally  receded,  leaving  the  nasal  appressed  to  the  ventral  surface  of  the 
frontal.  Some  support  may  be  given  to  this  line  of  reasoning  by  the  fact  that  a  fissure 
had  appeared  in  the  underlying  frontal  in  one  of  the  cranial  fragments  of  F elsinotherium 
serresii 2  found  at  Montpellier,  France,  exposing  the  ventral  face  of  the  nasal  in  the 
roof  of  the  olfactory  chamber.  Another  explanation  would  be  that  the  facial  process 
of  the  premaxilla  receded  from  the  posterior  border  of  the  meso-rostral  fossa  in  some 
stage  unknown  to  us  at  present,  carrying  the  nasal  forward  with  it.  Then  after  the 

1  P.  Gervais,  Zoologie  et  Paleontologie  franpaises,  Paris,  ed.  2,  Atlas,  pi.  6,  fig.  3,  1859;  C. 
Deperet,  Sur  la  reconstitution  d’un  squelette  de  Felsinotherium  Serresi,  Sirenien  pliocene  des 
sables  de  Montpellier,  Comptes  Rendus  Acad.  Sci.  Paris,  tome  158,  No.  25,  pp.  1858-1862, 
text  fig.,  1914;  C.  Deperet  and  F.  Roman,  Le  Felsinotherium  serresi  des  sables  pliocenes  de  Mont¬ 
pellier  et  les  rameaux  phyletiques  des  sireniens  fossiles  de  l’ancien  Monde,  Archiv.  du  Mus. 
d’hist.  nat.  Lyon,  tome  12,  Mem.  4,  pp.  1-56,  pis.  1-7,  text  figs.  1-14,  1920. 

2  P.  Gervais,  Zoologie  et  Paleontologie  franpaises,  Paris,  ed.  2,  Atlas,  pi.  4,  figs.  1',  1,"  1859. 


62  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


nasal  had  migrated  forward  and  dropped  to  a  lower  level,  the  facial  process  of  the 
premaxilla  by  further  telescoping  of  the  rostral  and  cranial  portions  of  the  skull 
was  again  carried  backward  to  the  posterior  border  of  the  meso-rostral  fossa  and  this 
in  turn  forced  the  nasal  backward  within  the  olfactory  chamber.  For  purely  mechan¬ 
ical  reasons,  such  an  explanation  is  insufficient,  because  in  so  large  a  skull  as  that  of 
Hydrodamalis,  the  interlocking  of  the  rostral  and  facial  portions  of  the  skull  would  be 
greatly  weakened  by  a  recession  of  the  facial  process  of  the  premaxilla.  At  the  same 
time,  it  should  be  noted  that  the  facial  process  of  the  premaxilla  has  receded  or  at  least 
does  not  extent  backward  as  far  as  the  hinder  border  of  the  meso-rostral  fossa  in  some 
of  the  living  genera,  but  it  should  also  be  noted  that  the  skulls  of  these  sirenians  are 
relatively  small.  Neither  of  the  above  explanations  appear  plausible  in  the  light  of 
available  data  and  additional  fossil  types  will  be  necessary  to  demonstrate  the  modifica¬ 
tions  which  have  resulted  in  the  Hydrodamalis  type  of  skull. 

As  shown  in  the  figures  of  the  skull  of  Hydrodamalis  stelleri  given  by  Brandt,  1  thin 
plates  of  the  maxillae  meet  mesially  in  a  linear  suture  and  form  the  floor  of  the  meso- 
rostral  fossa.  Laterally,  each  maxilla  is  limited  in  its  dorsal  extension  by  the  overlying 
premaxilla.  On  the  sides,  the  premaxillae  bound  the  meso-rostral  fossa  superiorly  and 
constitute  most  of  the  lateral  margins  of  the  rostrum  as  well  as  the  entire  extremity. 
Posteriorly  on  the  floor  of  the  fossa,  a  narrow  trough-like  vomer  is  exposed,  but  it  does 
not  extend  forward  to  the  level  of  the  antorbital  notches.  No  vomer  is  shown  in  the 
figure  of  a  skull  of  Felsinotherium  serresii  given  by  Gervais.  These  inferior  portions  of 
the  maxillae  as  well  as  the  vomer  are  not  preserved  on  this  specimen  from  California. 

With  the  exception  of  the  nasals,  the  relations  and  general  appearance  of  the  various 
elements  which  comprise  the  structures  within  the  olfactory  chamber  of  this  fossil 
sirenian  skull  (pi.  10)  are  essentially  the  same  as  those  found  in  the  Hydrodamalis  skull. 
This  olfactory  chamber  lies  above  the  nasal  passages  as  in  the  latter  species.  On  each 
side  of  the  olfactory  chamber,  a  thin  hook-shaped  nasoturbinal  is  appressed  to  the 
upper  border  of  the  lateral  wall.  The  left  nasoturbinal  is  approximately  108  mm. 
long  and  53  mm.  deep  at  the  extremity.  At  the  level  of  the  anterior  margin  of  the 
nasal,  this  nasoturbinal  is  20  mm.  deep  and  its  maximum  width  in  this  region  is  10.2 
mm.;  the  extremity  or  processus  hamatus  exhibits  a  dorso-ventral  groove  and  is  some¬ 
what  rugose.  The  perpendicular  plate  of  the  mesethmoid  occupies  a  sagittal  position 
in  the  olfactory  chamber  and  divides  the  latter  into  two  cavities,  each  of  which  contains 
a  turbinated  bone — the  ethmoturbinal — with  at  least  three  folds;  posteriorly  this 
perpendicular  septum  merges  into  the  transversely  placed  cribriform  plate  which  closes 
the  frontal  fontanelle.  In  its  present  imperfect  condition,  the  anterior  extremity  of 
the  mesethmoid  measures  50  mm.  in  depth  and  8  mm.  in  width  in  the  most  expanded 
portion.  It  terminates  some  36  mm.  below  the  roof  of  the  olfactory  chamber.  Orig¬ 
inally,  the  mesethmoid  may  have  extended  further  forward.  As  seen  from  a  frontal 
view,  the  mesethmoid  in  the  Hydrodamalis  skull  is  expanded  between  the  level  of  the 
inferior  borders  of  the  ethmoturbinals  and  the  nasal  passages,  but  is  relatively  narrow 
above  and  below  this  swelling.  Superiorly,  it  terminates  20  mm.  below  the  roof  of 
the  olfactory  chamber;  the  dorso-ventral  diameter  of  the  mesethmoid  is  93  mm.  at  the 
extremity  and  its  greatest  width  is  23  mm.  In  so  far  as  can  be  determined  from  the 
extremities  and  the  other  fragments  of  the  ethmoturbinals  which  are  preserved,  they 
resemble  those  of  Hydrodamalis.  Their  maximum  length  appears  to  have  been  about 
60  mm.  The  crista  galli  measures  60  mm.  in  depth  and  21.5  mm.  in  width.  It  resem¬ 
bles  that  of  Trichechus  in  that  it  is  swollen  interiorly  and  narrowed  superiorly.  In  the 
Hydrodamalis  skull  the  crista  galli  does  not  appear  to  be  developed  and  if  present  is 
merely  a  flat  structure  which  does  not  project  posteriorly  beyond  the  level  of  the  cribri¬ 
form  plate.  In  Metaxytherium  jordani  it  projects  approximately  35  mm.  beyond  the 
cribriform  plate.  The  bones  which  contribute  the  walls  for  the  nasal  passages  are  for 

1  J.  F.  Brandt,  Symbolae  Sirenologicae,  Fasciculus  II  et  III,  Mem.  Acad.  Imp.  Sci.  de  St 
Petersbourg,  ser.  7,  tome  12,  No.  1,  pi.  1,  May,  1868. 


A  Fossil  Sirenian. 


63 


the  most  part  missing;  the  pair  of  thin  bones  known  as  the  lamina  terminalis  of  the 
ethmoid  which  form  the  roof  above  the  nasal  passages  are  incomplete. 

In  general  outlines,  the  braincase  of  this  fossil  sirenian  agrees  very  closely  with  that 
of  F elsinotherium  serresii.  Comparative  measurements  indicate  that  the  ratio  between 
the  lengths  of  the  corresponding  portions  of  the  skull  of  this  sirenian  and  that  of 
F elsinotherium  serresii  is  as  6  :  5.  The  anterior  part  of  the  roof  of  the  cranium  is 
formed  by  the  frontals.  Above  the  olfactory  chamber,  the  anterior  borders  of  the 
frontals  are  overlain  by  the  comparatively  large  nasals,  between  which  a  narrow  strip 
of  each  bone  is  exposed  which  extends  forward  to  the  meso-rostral  fossa,  thus  complete¬ 
ly  separating  the  nasals  in  the  middle  line.  Outside  the  nasals,  the  postorbital  pro¬ 
cesses  of  the  frontals  are  in  contact  with  the  facial  processes  of  the  premaxillae,  which 
in  turn  define  the  borders  of  the  meso-rostral  fossa.  Along  the  mid-line,  from  before 
backward,  the  dorsal  surface  of  the  skull  is  elevated  between  the  nasals,  depressed  on 
each  side  in  the  intertemporal  region,  and  set  off  from  the  sides  of  the  braincase  by 
well-defined  temporal  ridges.  These  temporal  ridges  extend  backward  as  far  as  the 
occiput  and  disappear  anteriorly  on  the  postorbital  processes  of  the  frontals. 

In  front  of  the  lambdoidal  crest  the  roof  of  the  cranium  formed  by  the  parietals  is 
slightly  convex  both  from  side  to  side  and  from  before  backward.  In  front  of  these 
bones  the  surface  is  slightly  depressed  below  the  somewhat  prominent  temporal  ridges 
which  form  the  angles  between  the  roof  and  the  nearly  vertical  sides  of  the  temporal 
fossae.  Along  the  median  line,  as  mentioned  above,  the  surface  in  the  intertemporal 
region  is  elevated,  but  laterally  there  are  longitudinal  depressions  which  parallel  the 
temporal  ridges.  The  narrowest  part  of  the  skull  roof  is  about  60  mm.  in  front  of  the 
lambdoidal  crest;  at  this  point  the  width  is  72  mm.,  but  behind  this  the  roof  widens 
slightly  to  its  posterior  border,  where  it  measures  approximately  105  mm.  across. 
Anteriorly  it  attains  a  greater  width,  and  at  the  level  of  the  antero-mesial  portions  of 
the  frontals  it  is  138  mm.  wide.  The  sides  of  the  cranium  immediately  in  front  of  the 
supraoccipital  slope  to  the  base  of  the  zygomatic  processes,  but  further  forward  are 
nearly  flat  and,  as  already  remarked,  almost  vertical ;  in  the  latter  region  the  walls  of 
the  cranium  are  somewhat  thinner  than  in  the  middle  of  the  skull  roof  where  the 
parietals  attain  a  thickness  of  27  mm.  or  more. 

The  margins  of  the  left  nasal  are  so  smoothly  mortised  into  the  corresponding  frontal, 
that  its  presence  was  not  noted  until  the  skull  was  thoroughly  cleaned  in  preparation 
for  illustration.  In  position  the  left  nasal  agrees  more  closely  with  that  of  Metaxy- 
therium  cuvieri 1  than  with  F elsinotherium  serresii.  In  the  latter,  the  nasals  are  almost 
in  contact  on  the  mid-line  of  the  skull,  concealing  the  antero-mesial  portions  of  the 
frontals,  while  in  Metaxytherium  cuvieri  the  nasals  are  separated  by  an  interval  equival¬ 
ent  to  the  maximum  width  of  either  nasal.  This  interval  may  possibly  decrease  with 
age.  The  width  of  the  exposed  antero-mesial  portion  of  the  left  frontal  on  this  skull 
from  California  is  slightly  less  than  one-half  of  the  maximum  width  of  the  left  nasal. 
The  greatest  antero-posterior  diameter  of  the  left  nasal  is  47  mm.  and  transversely  it 
measures  28.5  mm.  It  is  somewhat  thinner  posteriorly,  but  measures  at  least  12.5 
mm.  in  depth  laterally  near  the  anterior  margin.  Internally,  there  is  a  distinct  line  of 
cleavage  between  the  nasal  and  the  frontal,  but  posteriorly  and  laterally  it  is  over¬ 
ridden  by  the  thin  edge  of  the  frontal  and  in  places  appears  to  be  irregularly  fused  with 
the  latter.  Anteriorly,  about  15  mm.  of  the  internal  margin  of  the  nasal  appears  on 
the  upper  rim  of  the  meso-rostral  fossa  between  the  frontal  and  the  premaxilla.  An- 
tero-externally,  an  oblique  suture  defines  the  contact  between  the  nasal  and  the 
extremity  of  the  premaxilla. 

On  the  top  of  the  braincase,  each  frontal  is  relatively  narrow  (about  60  mm.)  and 
extends  backward  from  the  meso-rostral  fossa  to  the  middle  of  the  cerebral  fossa.  An¬ 
teriorly,  the  frontals  form  a  roof  above  a  relatively  short  olfactory  chamber  as  com- 

1  H.  M.  D.  Blainville,  Osteographie  ou  description  iconographique,  Paris,  fasc.  15,  pp.13,  138- 
139,  Atlas,  pi.  8,  No.  1,  1843. 


64  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


pared  to  that  of  Hydrodamalis  and  are  applied  interiorly  to  the  upper  and  lateral  edges 
of  the  proximal  ends  of  the  nasoturbinals.  Their  anterolateral  extensions,  the  post¬ 
orbital  processes,  are  produced  forward  in  an  oblique  direction.  The  postorbital  pro¬ 
cesses  of  the  frontals  are  robust  as  in  Hydrodamalis,  but  are  triconvex  at  the  extremity, 
the  mesial  swelling  being  more  than  three  times  as  large  as  either  of  the  other  two.  The 
orbits  apparently  were  anterior  to  the  postorbital  processes  of  the  frontals,  although 
this  can  not  be  determined  with  certainty  because  the  jugal  and  that  portion  of  the 
maxilla  which  form  the  lower  rim  of  the  orbit  are  missing.  This  is  the  position  of  the 
orbit  in  Hydrodamalis  stelleri  and  Felsinotherium  serresii.  Each  frontal  is  overspread 
posteriorly  by  a  thin  process  of  the  corresponding  parietal.  The  shape  of  the  suture  is 
shown  on  plate  10.  The  parietals  and  squamosals  contribute  the  major  portion  of  the 
upper  and  lateral  walls  of  the  braincase.  The  longest  antero-posterior  diameter  of 
either  parietal  (171  mm.)  is  along  the  temporal  ridge,  as  they  are  separated  anteriorly 
and  mesially  by  the  frontals.  Posteriorly,  the  parietals  abut  against  the  upper  margin 
of  the  supraoccipital.  The  left  squamosal  with  its  lateral  process  is  missing.  The 
right  squamosal  is  imperfectly  preserved  and  all  of  the  zygomatic  process  has  been 
lost.  For  the  purposes  of  comparison,  the  description  of  the  external  boundaries  of 
the  squamosal  may  start  at  the  anterior  margin  of  the  tympano-periotic  recess  where 
the  squamosal  meets  the  alisphenoid  edge  to  edge  as  far  forward  as  the  posterior  margin 
of  the  temporal  fossa  and,  after  overlapping  the  hinder  margin  of  the  alisphenoid  to  its 
upper  extremity  on  the  side  of  the  cranium,  turns  sharply  backward  and  overspreads 
the  parietal,  with  the  suture  running  upward  in  a  general  oblique  direction  to  the 
lambdoidal  crest ;  the  suture  which  defines  the  posterior  limits  extends  downward  be¬ 
tween  the  squamosal  in  front  and  the  supraoccipital  and  exoccipital  on  the  rear  to  the 
tympano-periotic  recess. 

On  comparing  Trichechus  latirostris  and  Felsinotherium  serresii  with  this  fossil,  cer¬ 
tain  features  in  the  supraoccipital  shield  were  found  to  be  common  to  all  three.  The 
apical  portion  alone  of  the  occipital  shield  is  preserved  on  this  cranium  from  California 
and  this  fragment  measures  65  mm.  in  depth.  With  regard  to  the  occipital  shield,  it  is 
unfortunate  that  the  inferior  portions,  including  the  exoccipitals  and  condyies,  are 
missing  from  the  skull  of  this  fossil  sirenian.  In  so  far  as  the  occipital  shield  is  shown 
on  skulls  of  Metaxytherium,  there  is  no  close  resemblance  to  the  condition  of  the  shield 
in  Hydrodamalis.  The  lambdoidal  crest  formed  by  the  upper  margins  of  the  supra¬ 
occipital  resembles  that  of  Trichechus.  There  is  a  narrow  median  carina,  10  mm.  in 
width,  on  the  apical  portion  of  the  supraoccipital  and  on  each  side  there  is  a  small  con¬ 
cavity.  Below  the  level  of  the  top  of  the  braincase,  the  course  of  the  lambdoidal  crest 
can  not  be  determined  for  the  posterior  extremities  of  both  squamosals  are  damaged. 
In  Trichechus  the  lambdoidal  crest  passes  downward  across  the  squamosal  and  behind 
this  crest  a  portion  of  the  periotic  makes  its  appearance  on  the  lateral  face  of  the 
cranium  in  a  fontanelle  between  the  squamosal  and  exoccipital. 

The  cerebral  cavity  is  similar  to  that  of  Trichechus  in  most  respects,  but  differs  in 
some  minor  details.  In  shape,  it  is  rather  elongated,  laterally  compressed,  truncated 
anteriorly  by  the  frontals  which  constitute  the  rostral  wall  of  the  braincase  and  pos¬ 
teriorly  by  the  supraoccipital.  From  an  inferior  view,  it  will  be  noted  that  the  pos¬ 
terior  extremities  of  the  parietals  taken  together  form  a  narrow  transverse  shelf  at  a 
level  about  26  mm.  below  the  roof  of  the  cerebral  fossa.  Turning  to  the  roof  of  the 
fossa  for  each  cerebral  hemisphere,  we  find  that  the  parietal  constitutes  a  somewhat 
larger  area  than  the  frontal,  although  as  regards  length  these  two  elements  are  about 
equal.  The  longitudinal  median  carina  which  separates  the  temporal  lobes  of  the 
cerebrum  does  not  extend  forward  to  the  crista  galli  as  in  Trichechus,  but  flattens  out 
at  a  point  approximately  15  mm.  posterior  to  the  suture  between  the  parietals  and 
frontals.  Along  the  suture  between  the  frontals  there  is  a  median  longitudinal  depres¬ 
sion  and  on  each  side  of  this  there  is  a  curved  ridge.  In  Trichechus,  the  part  of  the 


A  Fossil  Sirenian. 


65 


roof  contributed  by  the  parietals  is  much  shorter  than  that  contributed  by  the 
frontals. 

The  endocranial  cast  (pi.  9)  here  discussed  is  not  complete  for  the  lower  occipital  re¬ 
gion  and  basicranium  of  this  skull  were  missing.  It  is  of  considerable  interest  because 
it  is  not  unlike  that  of  Trichechus  latirostris 1  and  the  Upper  Eocene  Eotheroides  aegyp- 
tiacum,1 2  but  the  proportions  of  the  frontal  and  temporal  lobes  of  the  cerebrum  are 
somewhat  different  from  Hydrodamalis  stelleri .3  It  is  unlikely  that  such  striking 
similarities  would  exist  in  the  absence  of  some  close  relationship  between  Metaxy- 
therium  and  Trichechus.  A  cast  of  the  entire  cranial  cavity  of  a  Metaxytherium  skull 
will  of  necessity  be  needed  to  demonstrate  or  disprove  any  filial  relationship. 

All  comparisons  will  be  limited  to  features  observable  from  a  dorsal  view.  It  is 
to  be  noted  that  the  small  olfactory  lobes  are  attached  anteriorly  in  a  nipple-like 
fashion  to  the  frontal  lobes  of  the  cerebrum.  The  cerebral  hemispheres  are  set  off 
from  one  another  sagittally  by  a  narrow  elevation  anteriorly  and  by  a  sinus  poste¬ 
riorly.  Each  is  divided  into  an  expanded  frontal  lobe  and  an  elongate  temporal  lobe  by 
a  lateral  depression  which  increases  in  depth  interiorly.  This  appears  to  be  the  pseu- 
dosylvian  depression.  The  breadth  of  the  right  frontal  lobe  of  the  cerebrum  is  49 
mm.  and  the  maximum  length  of  the  entire  right  hemisphere  is  122  mm.  Behind  and 
below  the  sagittal  sinus,  there  appears  a  median  tentorial  depression.  The  cerebellum 
is  relatively  small,  but  its  posterior  limits  can  not  be  determined  with  certainty. 

Behind  the  palate  in  skulls  of  Trichechus  and  Hydrodamalis  and  on  each  side  of  the 
posterior  aperture  of  the  nasal  passages,  there  is  a  rough  irregular  descending  process 
formed  by  the  fusion  of  the  palatine,  pterygoid,  and  the  pterygoid  plate  of  the  ali- 
sphenoid.  On  this  fossil  skull  the  pterygoid  processes  of  the  alisphenoid  have  been 
broken  off  at  the  base.  At  this  level,  the  left  process  measures  64  mm.  in  length.  As 
a  result  of  the  above-mentioned  breakage,  the  basisphenoid  was  also  lost,  exposing 
the  entire  course  of  the  foramen  rotundum.  The  groove  for  the  foramen  rotundum 
commences  at  a  point  about  20  mm.  in  front  of  the  posterior  margin  of  the  pterygoid 
process  of  the  alisphenoid  and  curving  around  the  base  of  that  process  is  continued  for¬ 
ward  to  its  ectal  orifice  within  the  temporal  fossa.  This  foramen  is  bounded  externally, 
superiorly,  and  interiorly  by  the  alisphenoid,  and  internally  by  the  orbitosphenoid, 
paralleling  the  condition  found  in  the  Trichechus  skull.  In  so  far  as  this  specimen  is 
preserved,  the  fissures  and  foramina  within  the  temporal  fossae  do  not  appear  to  differ 
from  those  found  in  the  Trichechus  skull. 

On  the  basis  of  measurements,  the  periotic  of  Hydrodamalis  is  about  one-eighth  larger 
than  that  of  this  fossil  sirenian.  The  tympanic  ring  is  missing,  but  in  so  far  as  the 
left  periotic  is  preserved  it  resembles  that  of  Hydrodamalis  very  closely.  The  anterior 
and  posterior  processes  are  heavy  and  rounded.  The  cochlear  portion  of  the  periotic 
is  missing,  but  the  interior  margins  of  the  fenestra  rotundum  and  fenestra  ovalis  are 
present.  These  fenestrae  were  similar  in  position  to  those  of  Hydrodamalis.  Instead 
of  the  aquaeductus  vestihuli  opening  into  a  fissure  in  a  large  depression  as  in  Hydro¬ 
damalis,  the  depression  lies  above  the  orifice  of  the  aquaeduct.  The  stapes  resembles 
that  of  Trichechus  more  closely  than  that  of  Hydrodamalis.  It  measures  14.8  mm.  in 
length  and  the  perforation  is  situated  4.4  mm.  above  the  footplate.  The  malleus 
and  incus  are  damaged,  but  exhibit  the  characteristic  sirenian  structural  peculiarities. 

1  J.  F.  Brandt,  Symbolae  Sirenologicae,  Fasciculus  II  et  III.  M6m.  Acad.  Imp.  Sci.  de  St.- 
Petersbourg,  ser.  7,  tome  12,  No.  1,  pi.  9.  fig.  1,  1868. 

2  O.  Abel,  Die  eocanen  Sirenen  der  Mittelmeerregion,  Palaeontographica,  Stuttgart,  Bd.  59, 
Lief.  5-6,  pi.  33,  fig.  4,  1913. 

3  J.  F.  Brandt,  op.  cit.,  pi.  9.  fig.  3. 


66  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


Measurements  of  the  skull. 


Metaxytherium 
jordani  Lompoc, 
California  Cat. 
No.  10,  Stanford 
University. 

Hydrodamalis 
stelleri  Bering 
Island  Cat. 

No.  218326, 

U.  S.  N.  M. 

mm. 

mm. 

Condylobasal  length  of  skull . 

X 

673 

Left  condyle  to  extremity  of  left  postorbital  process  of 

frontal . . . 

X 

380 

Posterior  margin  of  parietal  to  anterior  angle  of  post- 

orbital  process  of  left  frontal . 

316 

312 

Breadth  across  combined  parietals . 

101 

138 

Breadth  across  combined  frontals  (least  intertemporal 

breadth) . 

122 

95 

Breadth  across  extremities  of  postorbital  processes  of 

frontals . 

i  198 

192 

Length  of  left  premaxilla . 

X 

372 

Greatest  transverse  diameter  of  dorsal  border  of  pre- 

maxilla  along  meso-rostral  fossa . 

49 

42.3 

Length  of  meso-rostral  fossa . . 

X 

237 

Greatest  breadth  of  meso-rostral  fossa . 

i  72 

95 

Greatest  zygomatic  breadth . 

X 

317 

Length  of  zygomatic  process  of  right  squamosal . 

X 

180.5 

Greatest  width  of  skull  across  arches  below  orbits . 

X 

262 

Posterior  margin  of  zygomatic  process  to  anterior 

margin  of  jugal  in  rim  of  orbit . 

X 

285 

Breadth  across  pterygoid  processes  of  alisphenoid  at 

base  (outside  measurements) . 

118 

108 

Antero-posterior  diameter  of  right  parietal . 

164 

165.5 

1  Estimated. 


Dorsal  Vertebrae. 

The  large  number  of  dorsal  vertebrae  and  the  heavy  ribs  which  they  support 
increase  the  weight  of  the  sirenian  skeleton.  Dollo  has  even  supposed  that  these 
enlarged  ribs  protected  the  vital  organs  against  some  unknown  enemies.  According 
to  Abel,  a  skeleton  of  Metaxytherium  comprises  7  cervical,  19  dorsal,  3  (?)  lumbar,  and 
25  (?)  caudal  vertebrae.  Dr.  Zoltan  Schreter1  has  also  discussed  the  skeleton  of 
Metaxytherium ,  but  the  writer  has  been  unable  to  consult  this  paper.  Deperet  states 
that  the  skeleton  of  Felsinotherium  serresii  consists  of  7  cervicals,  19  dorsals,  3  lumbars, 
1  sacral,  and  25  (?)  caudal  vertebrae.  Only  four  of  the  dorsal  vertebrae  of  this  sirenian 
are  known.  Three  of  these  vertebrae  were  found  embedded  in  their  normal  position 
in  an  irregular  mass  of  opal.  The  remaining  dorsal  vertebrae  was  freed  from  another 
block  of  matrix.  The  last  dorsal  in  the  above-mentioned  series  lacks  the  posterior  end 
of  the  centrum.  The  exposed  surface  is  weathered  and  black  in  color  which  suggests 
that  the  fracture  is  very  old.  Some  of  the  skeleton  was  undoubtedly  lost  subsequent 
to  the  discovery  for  no  contact  could  be  obtained  between  the  several  masses  of  matrix 
which  were  included  in  the  shipment. 

Although  there  is  some  regional  differentiation  of  the  dorsal  vertebrae  in  living 
sirenians,  such  as  the  contour  and  length  of  the  centra,  the  invariable  occurrence  of  a 
single  facet  for  the  head  of  the  rib  on  the  posterior  dorsals  and  the  presence  of  a  pair 
of  demi-facets  on  the  anterior  dorsals,  allocations  made  on  this  basis  are  always  at¬ 
tended  with  some  uncertainty.  The  centra  of  the  first  three  dorsals  are  usually  com¬ 
pressed  in  a  dorso-ventral  direction.  The  centra  of  these  vertebrae  are  also  consider- 

1  Z.  Schreter,  Mediterranes  Metaxytherium  Skelett,  v.  Marcyfalva,  Foldt,  Kozlony,  Buda¬ 
pest,  Bd.  47,  pp.  176-177.  1917. 


A  Fossil  Sirenian. 


67 


ably  smaller  than  those  that  follow,  and  a  line  drawn  through  the  centers  of  the  facets 
for  the  tubercula  would  slope  downward  and  forward  from  the  fifth  to  the  first  dorsal. 
From  this  point  backward,  the  centra  assume  a  heart-shaped  outline,  and  near  the 
middle  of  the  series  a  hyapophysis  is  developed  on  the  inferior  face.  The  centra  of  the 
dorsal  vertebrae  also  increase  in  length  from  the  first  to  the  last. 

There  appears  to  be  no  correlation  between  the  total  number  of  vertebrae  in  the 
dorsal  series  and  the  number  which  bear  demi-facets  for  heads  of  ribs.  No  differences 
in  the  manner  of  the  insertion  of  the  ribs  on  the  dorsal  series  are  apparent,  yet  the  ratios 
between  the  dorsals  bearing  demi-facets  and  those  with  single  facets  in  the  genera 
hereinafter  mentioned  reveal  some  interesting  anatomical  details.  The  skeleton  of 
the  Miocene  sirenian,  Miosiren  kocJd,1  contained  20  dorsals,  of  which  17  had  demi- 
facets  and  3  single  facets.  On  the  other  hand,  the  Oligocene  sirenian,  Halitherium 
schinzi,2  had  only  19  dorsals,  and  of  these  12  possessed  demi-facets.  The  Pliocene 
Felsinotherium  serresii  also  had  19  dorsals,  but  only  9  of  these  possessed  demi-facets. 
Turning  to  the  recent  sirenians,  we  find  that  Halicore  australis  and  Hydrodamalis 
steUeri  have  19  dorsals,  but  only  7  of  these  have  demi-facets.  Yet  in  the  case  of 
Trichechus  latirostris  which  has  only  18  dorsals,  there  are  13  with  demi-facets. 

The  isolated  dorsal  appears  to  be  the  fourth.  The  three  which  were  found  associated 
together  belong  in  the  column  somewhere  between  the  sixth  and  ninth  and  there 
appears  to  be  some  justification  for  referring  to  them  as  the  sixth,  seventh,  and  eighth 
dorsals.  After  comparing  the  recent  types,  it  became  apparent  that  within  genera 
there  were  definite  limits  to  the  number  of  dorsal  vertebrae  bearing  a  hyapophysis  and 
whereas  a  hyapophysis  was  present  on  the  sixth  dorsal  of  Trichechus  latirostris,  it  did 
not  appear  in  the  skeleton  of  Hydrodamalis  stelleri  anterior  to  the  eleventh  dorsal. 
No  indication  of  a  hyapophysis  is  present  on  the  centra  of  these  dorsals  and  this  may 
be  cited  as  an  additional  reason  for  the  above-mentioned  allocations.  The  posterior 
dorsals  of  Metaxytherium  krahidetzi  do  possess  a  hyapophysis.  Aside  from  their 
larger  size,  these  vertebrae  do  not  differ  structurally  from  those  of  Felsinotherium 
serresii .3  They  are  also  considerably  larger  than  those  of  Metaxytherium  cuvieri ,4 
Metaxytherium  krahidetzi ,5  and  Metaxytherium  floridanum. 

The  dorsal  which  is  considered  to  be  the  fourth  in  the  series,  although  strikingly 
different  in  proportions,  presents  the  majority  of  the  features  which  characterize  the 
same  vertebra  of  Trichechus  latirostris.  It  was  situated  anterior  to  the  others  for  the 
following  reasons:  the  centrum  is  smaller  and  shallower;  the  anterior  and  posterior 
demi-facets  on  the  lateral  face  of  the  centrum  are  nearly  equal  in  size  and  are  separated 
by  an  interval  of  less  than  5  mm.;  the  neural  canal  is  higher;  and  the  internal  borders  of 
the  prezygapophysial  facets  are  higher  than  the  external.  Compared  with  the  same 
vertebra  in  a  Hydrodamalis  skeleton,  the  principal  differences  are  as  follows:  the  diapo¬ 
physes  are  relatively  shorter;  the  upper  portions  of  the  neural  arches  are  thicker,  more 
robust,  and  much  shorter;  and  the  lateral  demi-facets  are  relatively  larger. 

Of  the  three  remaining  dorsals,  the  middle  one  is  the  most  complete.  This  dorsal 
(pi.  11,  fig.  2),  which  will  be  referred  to  as  the  seventh,  is  characterized  by  a  broad 
heart-shaped  centrum,  a  nearly  circular  neural  canal  with  a  slit-like  apex,  and  by  the 
presence  of  a  pair  of  demi-facets,  the  anterior  of  which  is  the  largest.  The  anterior 
demi-facet  (pi.  11,  fig.  5)  extends  upward  from  the  level  of  the  widest  part  of  the 

1  L.  Dollo,  Premiere  note  sur  les  Sir6niens  de  Boom  (Resume),  Proces-Verbaux  Soc.  Beige 
G6ol,  Paleont.  et  d’Hydrol.,  Bruxelles,  tome  3,  p.  418,  1889;  C.  Deperet  and  F.  Roman,  Archiv. 
du  Mus.  d’hist.  nat.  Lyon,  tome  12,  Mem.  4,  text  fig.  8,  No.  Ill,  1920. 

2  G.  R.  Lepsius,  Halitherium  schinzi,  die  fossile  Sirene  des  Mainzer  Beckens,  Abhandl. 
Mittelrhein,  geol.  Vereins,  Darmstadt,  Bd.  1,  Lief.  1-2,  pp.  4  +  200  +  viii,  pis.  1-10,  1881-1882. 

3  C.  Deperet  and  F.  Roman,  Le  Felsinotherium  serresi  des  sables  pliocenes  de  Montpellier  et 
les  rameaux  phyletiques  des  sireniens  fossiles  de  l’ancien  Monde,  Archiv.  du  Mus.  d’hist.  nat. 
Lyon,  tome  12,  Mem.  4,  pp.  14-16,  pi.  6.  1920. 

4  H.  M.  D.  Blainville,  Osteographie  ou  description  iconographique,  Paris,  fasc.  15,  pi.  8,  1843. 

6  O.  Abel,  Die  Sirenen  der  mediterranen  Tertiarbildungen  Osterreichs,  Abhandl.  k.  k.  geol. 

Reichsanstalt,  Bd.  19,  Heft  2,  pp.  91-93,  pi.  6,  figs.  2-4,  1904. 


68  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


centrum  almost  to  the  level  of  the  top  of  the  neural  canal.  This  facet  is  concave  and  is 
twisted  slightly  from  the  antero-inferior  angle  to  the  postero-superior  angle.  It  is 
elliptical  in  outline  and  measures  60  mm.  in  depth  and  31.5  in  breadth.  Interiorly, 
the  posterior  demi-facet  also  reaches  the  widest  point  of  the  centrum  and  extends 
superiorly  above  the  level  of  the  top  of  the  centrum,  giving  rise  to  a  postero-lateral 
protuberance.  The  facet  is  obliquely  placed  on  this  protuberance  and  measures  36 
mm.  in  depth  and  23  mm.  in  breadth.  An  interval  of  30  mm.  separates  the  two  facets. 
The  margins  of  both  demi-facets  are  well  defined.  'The  prezygapophysial  facets  are 
concave,  curving  upward  and  outward.  The  lateral  and  inferior  faces  of  the  centrum 
are  concave.  There  is  no  trace  of  a  hyapophysis.  The  neural  arch  is  very  heavy  and 
on  each  side  gives  rise  to  a  short  lateral  process,  the  diapophysis.  The  neurapophysis 
does  not  extend  the  full  length  of  the  centrum;  the  posterior  border  is  curved  and  is 
separated  from  the  posterior  demi-facet  by  an  interval  greater  than  the  maximum 
breadth  of  the  latter.  The  neural  spines  are  incomplete  on  all  of  the  dorsals  shown  on 
plate  11,  but  the  extremities  of  two  additional  spines  were  found  in  another  piece  of 
matrix.  These  extremities  are  expanded  laterally  and  flattened  superiorly.  The 
spines  are  inclined  backward  on  all  four  of  the  dorsal  vertebrae. 

The  sixth  (pi.  11,  fig.  1)  and  eighth  dorsals  (pi.  11,  fig.  3)  are  very  similar  in  appearance 
to  the  seventh.  The  most  apparent  differences  are  in  the  lengths  of  the  centra  and  in 
the  curvature  of  the  prezygapophysial  facets.  There  is  little  difference  in  the  sixth, 
seventh,  and  eighth  dorsals  (pi.  11)  in  the  position  and  proportions  of  the  demi-facets. 
The  presence  of  these  demi-facets  shows  that  the  articulation  of  the  head  of  the  rib 
was  divided  between  two  vertebrae.  The  prezygapophysial  facets  are  somewhat 
flattened  on  the  sixth  dorsal,  sloping  outward  and  forward;  the  internal  face  of  the 
metapophysis  at  the  outer  margin  of  this  facet  is  excavated.  The  curvature  of  the 
prezygapophysial  facets  of  this  dorsal  is  in  sharp  contrast  to  the  seventh  and  eighth  on 
which  the  facets  are  concave  from  side  to  side  and  curve  upward  above  the  level  of  the 
top  of  the  metapophysis.  The  interval  between  the  inner  borders  of  the  prezygapo¬ 
physial  facets  apparently  increases  from  the  fourth  dorsal  to  the  middle  of  the  series, 
for  it  is  much  narrower  on  the  fourth  than  on  the  eighth,  the  measurements  for  the  four 
vertebrae  being  22.5,  27.5,  33.,  and  36.5  mm.  A  similar  condition  is  present  in  the 
skeleton  of  Trichechus  latirostris  where  the  interval  between  the  prezygapophysial 
facets  decreases  from  the  first  to  the  fifth  dorsal,  then  increases  to  the  fourteenth,  and 
decreases  slightly  from  this  vertebra  to  the  end  of  the  series.  Attention  should  also  be 
directed  to  the  groove  which  commences  at  the  base  of  the  neural  spine  and  curves 
forward  below  the  inner  margin  of  each  prezygapophysial  facet  on  all  of  these  dorsals. 
The  metapophyses  of  the  fourth,  sixth,  seventh,  and  eighth  dorsals  project  beyond  the 
level  of  the  anterior  epiphysis.  The  postzygapophysial  facets  of  the  sixth  and  seventh 
dorsals  are  elongate,  quadrangular  in  outline,  and  slope  obliquely  upward  from  the 
internal  to  the  external  margin. 

The  anterior  and  posterior  faces  (pi.  11)  of  the  centra  of  these  dorsal  vertebrae  are 
broadly  heart-shaped  in  outline.  The  epiphyses  appear  to  be  thin,  though  com¬ 
plete  and  fully  ossified.  The  condition  of  the  epiphysis  in  the  several  species  of 
Metaxytherium  now  known  is  an  interesting  subject,  for  there  appears  to  be  a  tend¬ 
ency  toward  the  reduction  of  the  epiphyses  in  some  of  the  species.  In  the  case  of 
Metaxytherium  krahuletzi,  according  to  Abel,  the  central  part  is  thin  and  pitted,  pre¬ 
senting  an  eroded  appearance;  the  peripheral  ring  is  solid  and  somewhat  thicker.  The 
vertebrae  of  Metaxytherium  floridanum  possess  epiphyses  of  the  same  type.  This  is 
interpreted  as  a  partial  degeneration  of  the  epiphysis  and  is  also  offered  as  a  possible 
explanation  of  the  condition  of  the  epiphysis  in  the  living  genera  Trichechus  and  Hali- 
core.  In  the  living  Manatee,  Trichechus ,  the  epiphysis  is  reduced  to  a  narrow  and  in¬ 
complete  ring,  while  in  Dugong,  Halicore,  it  has  disappeared  entirely.  On  these  four 
dorsal  vertebrae,  the  central  part  of  the  epiphysis  is  depressed,  but  the  pits  are  minute 
and  indistinct;  the  peripheral  border  is  marked  by  concentric  rings  and  the  margin  is 


A  Fossil  Sirenian. 


69 


raised  above  the  level  of  the  centrum.  These  dorsal  vertebrae  differ  from  those  of  the 
above-mentioned  species  of  Metaxytherium  in  that  the  epiphyses  have  not  reached  the 
same  stage  of  reduction,  although  the  former  are  considerably  larger  than  those  of  the 
latter. 

Measurements  of  the  dorsal  vertebrae  in  millimeters. 


4th 

Dorsal. 

6th 

Dorsal. 

7th 

Dorsal. 

8th 

Dorsal. 

Greatest  depth  (vertically)  of  vertebra,  tip  of  neural 

spine  to  inferior  face  of  centrum . 

199  + 

211  + 

234.5  + 

X 

Greatest  depth  of  neural  canal  anteriorly . 

55 

49 

52.3 

49 

Greatest  breadth  of  neural  canal  posteriorly . 

48.2 

42.5 

44 

45 

Height  of  anterior  face  of  centrum  (mesial) . 

64 

70 

73 

80 

Breadth  of  anterior  face  of  centrum . 

122 

124 

134.4 

138 

Height  of  posterior  face  of  centrum . 

62 

71.5 

76.5 

X 

Breadth  of  posterior  face  of  centrum . 

X 

139 

142 

X 

Length  of  centrum . 

60.5 

70.5 

72 

X 

Distance  across  vertebra  between  tips  of  diapophyses . . 

X 

171  + 

173  + 

X 

Distance  between  outside  margins  of  prezygapophysial 

facets . 

81 

90 

82 

92 

Distance  between  tip  of  right  prezygapophysis  and 

extremity  of  right  postzygapophysis . 

X 

107 

111 

X 

Length  of  right  prezygapophysial  facet . 

31.2 

32.5 

34.5 

33 

Length  of  right  postzygapophysial  facet . 

X 

35 

36.3 

X 

Minimum  length  of  neurapophysis . 

38.2 

47 

53.2 

52.7 

Antero-posterior  length  of  neural  spine  in  a  horizontal 

line  immediately  above  zygapophyses . 

X 

71 

X 

X 

Antero-posterior  diameter  of  diapophysis  at  extremity . 

X 

58  ± 

56± 

45 

Vertical  height  of  demi-facet  on  anterior  margin  of 

centrum . • . 

45.5 

50 

52.1 

51.5 

Antero-posterior  diameter  of  demi-facet  on  anterior 

margin  of  centrum . 

30.5 

26 

30 

X 

Vertical  height  of  neural  spine  (distance  between 

superior  margin  neural  canal  and  tip  of  spine) . 

X 

X 

114  + 

X 

Transverse  diameter  of  extremity  of  neural  spine . 

X 

X 

26.2 

X 

Distance  from  articular  face  of  prezygapophysial  facet 

to  inferior  margin  of  centrum . 

112 

126 

129.3 

136.5 

Ribs. 

All  of  the  ribs  associated  with  this  specimen  are  imperfect,  but  judging  from  the  six 
fragments  represented,  they  were  about  as  highly  specialized  as  those  of  Trichechus 
latirostris.  The  ribs  of  this  sirenian  were  very  robust;  the  shafts  narrow  abruptly 
near  the  tuberculum  and  their  curvature  is  no  more  pronounced  than  in  Trichechus. 
One  of  these  fragments  measures  67  mm.  in  width  and  43  mm.  in  thickness  below  the 
neck.  The  proximal  end  of  a  left  rib  (pi.  11,  fig.  10)  is  sufficiently  well  preserved  to 
show  the  peculiarities  of  the  tuberculum  and  capitulum.  The  capitulum  consists  of 
two  articular  facets  separated  superiorly  by  a  narrow  sinus.  The  anterior  one  of 
these  facets  is  flattened;  the  posterior  one  is  somewhat  convex.  They  are  placed 
obliquely  on  the  sides  and  end  of  the  neck,  but  do  not  extend  interiorly  upon  the  broad 
ventral  face  of  the  same.  The  tuberculum  is  rounded  and  rolls  over  upon  the  side  of 
the  neck.  The  shafts  of  these  ribs  appear  to  be  irregularly  swollen  below  the  tuber¬ 
culum,  but  the  contour  of  the  inferior  portions  is  more  or  less  uniform. 

Metacarpal. 

The  fifth  metacarpal  (pi.  11,  fig.  9)  of  the  left  hand  resembles  that  of  Halicore  in  its 
proportions.  The  proximal  end  measures  34.5  mm.  in  width  and  32.5  mm.  in  depth. 
Judging  from  the  position  of  the  facets  on  the  proximal  end  of  this  bone,  the  pisiforme 
and  ulnare  were  consolidated  as  in  Halicore.  The  facet  for  this  fused  carpal  is  large, 


70  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


occupying  the  major  portion  of  the  head,  and  is  moderately  concave.  On  the  internal 
face  between  this  facet  and  the  articular  surface  for  the  fourth  metacarpal,  there  is  a 
narrow  flattened  facet  for  the  unciform.  The  facet  for  articulation  with  the  corres¬ 
ponding  surface  on  the  fourth  metacarpal  is  convex.  Viewed  from  the  side,  the  dorsal 
contour  of  the  shaft  is  nearly  straight  while  the  palmar  border  is  curved.  The  distal 
extremity  is  expanded  laterally  and  compressed  in  a  dorso-palmar  direction.  The 
total  length  of  this  metacarpal  is  79  mm. 


IY.  NEW  PINNIPEDS  FROM  THE  MIOCENE  DIATOMACEOUS 
EARTH  NEAR  LOMPOC,  CALIFORNIA. 

Until  quite  recently,  the  pelagic  mammalian  fauna  of  the  diatoma¬ 
ceous-earth  series  in  California  was  unknown.  While  remains  of 
fossil  pelagic  mammals  are  encountered  in  many  marine  formations, 
the  collection  of  such  material  usually  depends  upon  the  degree  of 
hardness  of  the  rock  they  are  found  protruding  from  as  well  as  upon 
the  size  of  the  specimen.  Exploration  and  excavation  for  satisfac¬ 
tory  specimens  are  as  uncertain  in  marine  formations  as  elsewhere. 
The  commercial  use  of  diatomaceous  earth  has  made  possible  the 
exploration  and  excavation  of  this  marine  formation  to  a  considerable 
depth.  Through  the  interest  of  Mr.  Edward  B.  Starr,  superin¬ 
tendent  of  the  Celite  Products  Company,  many  specimens  which 
otherwise  would  have  been  lost  to  science  have  been  made  available 
for  study.  With  one  exception,  all  of  the  fossil  pelagic  mammals  now 
known  from  the  diatomaceous-earth  series  in  California  were  pre¬ 
served  through  his  efforts. 

All  of  the  fossil  pelagic  mammals  thus  far  obtained  from  the 
diatomaceous-earth  series  belong  to  a  fauna  which  does  not  appear  to 
occur  elsewhere  in  California.  The  otarids  which  occur  in  this 
deposit  represent  a  more  modernized  stock  than  the  archaic  types  of 
earlier  Miocene  stages,  such  as  Allodesmus  kernensis  and  Desmat- 
ophoca  oregonensis.  One  of  the  otarids  described  in  the  present 
paper  may  be  the  Miocene  prototype  of  the  living  fur  seal  of  the 
North  Pacific  Ocean.  Another  larger  species,  at  present  very  imper¬ 
fectly  known,  appears  to  belong  in  the  limited  group  which  includes 
the  living  members  of  the  family  Otariidae. 

As  far  as  the  cetacean  fauna  of  this  diatomaceous  series  is  known, 
it  comprises  a  modernized  assemblage  of  species  which  is  quite  differ¬ 
ent  from  the  fauna  which  occurs  in  the  limestones,  dolomites,  and 
sandstones  of  the  lower  division  of  the  Monterey  formation.  The 
whalebone  whales  of  the  diatomaceous-earth  series  are  unmistakably 
members  of  the  modernized  Mysticeti,  while  those  found  in  the  lower 
division  of  the  Monterey  belong  to  the  more  archaic  cetotheres. 
All  of  the  cetaceans  thus  far  obtained  from  the  diatomaceous-earth 
series,  so  far  as  can  be  judged  by  their  fragmentary  remains,  exhibit 
affinities,  more  or  less  remote,  with  species  now  living  in  the  Pacific 
Ocean.  The  little  finner,  Balaenoptera  ryani ,l  appears  to  be  related 

1  G.  D.  Hanna  and  M.  E.  McLellan,  A  new  species  of  whale  from  the  type  locality  of  the 
Monterey  Group,  Proc.  Calif.  Acad.  Sci.,  San  Francisco,  ser.  4,  vol.  13,  No.  4,  pp.  237-241, 
plates  5  to  9,  June  14,  1924. 


71 


72  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


to  the  living  sharp-head  finner  whale,  Balaenoptera  davidsoni.  The 
telescoping  of  the  occipital  and  facial  portions  of  this  skull  has  not 
advanced  as  far  as  in  the  living  species,  but  otherwise  the  resemblance 
is  remarkably  close.  Although  Megaptera  miocaena 1  appears  to  be 
related  to  the  existing  Pacific  humpback  whale,  Megaptera  versabilis , 
the  interdigitation  of  the  rostral  and  cranial  elements  of  the  skull  is 
not  as  far  advanced,  but  the  forward  thrust  of  the  supraoccipital 
shield  has  reached  an  extreme  stage  in  this  process.  Remains  of  only 
one  dolphin2  have  been  described.  The  relationships  of  the  sirenian 
Metaxytherium  jordani  have  been  discussed  in  a  preceding  chapter. 

As  for  Tertiary  otarids,  none  are  known  from  deposits  on  the  At¬ 
lantic  coast  of  North  America.  Differences  in  climate  or  lack  of. 
favorable  breeding-places  may  have  had  something  to  do  with  their 
apparent  absence  from  this  region.  Several  occurrences  have  already 
been  recorded  for  the  Pacific  coast,3  and  it  is  possible  that  some  of  the 
European  specimens  have  been  correctly  allocated  in  this  family. 

Living  otarids  are  distinguished  from  phocids  by  a  number  of 
anatomical  differences,  and  in  case  of  the  skeleton  the  following 
features  may  be  cited:  The  otarids  have  a  skull  with  well-developed 
postorbital  processes  and  an  alisphenoid  canal;  the  mastoid  process 
is  conspicuous,  distinct  from  the  small  auditory  bulla.  The  scapula 
is  large,  relatively  deep,  with  high  spine  near  the  glenoid  border,  a 
distinct  acromion  process,  and  large  prescapular  fossa.  The  humerus 
lacks  an  entepicondylar  foramen.  The  digits  of  the  manus  decrease 
in  size  from  the  first  to  the  fifth  and  do  not  possess  well-developed 
nails.  The  pubic  bones  are  unankylosed;  the  ilium  is  long  and 
slender,  slightly  curved  outward  anteriorly.  The  femur  possesses  a 
fairly  well-developed  lesser  trochanter.  Three  digits  (II,  III,  IV)  of 
the  pes  are  shorter  and  more  slender  than  the  others,  with  well- 
developed  nails.  The  hind  limbs  are  capable  of  being  turned  forward 
for  terrestrial  locomotion. 

The  phocids  have  a  skull  with  undeveloped  or  rudimentary  post¬ 
orbital  processes,  but  lack  an  alisphenoid  canal;  the  mastoid  process 
is  inflated,  continuous  with  the  auditory  bulla.  The  scapula  is  usually 
falciform,  with  spine  near  the  middle  of  the  blade,  a  slightly  developed 
acromion  process,  and  with  prescapular  fossa  rarely  larger  than  post¬ 
scapular  fossa.  An  entepicondylar  foramen  is  present  in  the  humerus 
of  many  of  the  genera.  The  digits  of  the  manus  are  subequal, 

1  R.  Kellogg,  Description  of  the  skull  of  Megaptera  miocaena ,  a  fossil  humpback  whale  from 
the  Miocene  diatomaceous  earth  of  Lompoc,  California,  Proc.  U.  S.  Nat.  Mus.,  vol.  61,  Publ. 
2435,  pp.  1-18,  plates  1  to  4,  July  3,  1922.  [This  specimen  was  found  900  feet  north  from  the 
northeast  corner  of  the  SE.  of  Section  15,  Township  6  North,  Range  34  West,  San  Bernardino 
Base  and  Meridian,  2  miles  south  and  east  of  Lompoc,  Santa  Barbara  County,  California.] 

2  D.  S.  Jordan  and  J.  Z.  Gilbert,  Fossil  fishes  of  Southern  California,  Leland  Stanford  Junior 
University  Publications,  Univ.  Ser.,  pp.  59-60,  plate  28,  figs.  1,  3,  1919.  W.  Palmer,  Journ. 
Mammalogy,  Baltimore,  vol.  1,  No.  2,  p.  100,  February  1920. 

3  R.  Kellogg,  Pinnipeds  from  Miocene  and  Pleistocene  deposits  of  California,  Bull.  Dept. 
Geol.  Sci.,  Univ.  Calif.  Publ.,  Berkeley,  vol.  13,  No.  4,  pp.  23-132,  text  figs.  1  to  19,  April  14,  1922. 


New  Pinnipeds  from  Vicinity  of  Lompoc,  California.  73 

usually  decreasing  slightly  from  the  first  to  the  fifth;  the  nails  usually 
are  well-developed.  The  pubic  bones  are  approximated  in  the 
females  and  appressed  posteriorly  for  about  one-third  of  their  length 
in  the  males;  the  ilium  is  short  and  broad,  strongly  curved  outward 
anteriorly.  The  lesser  trochanter  is  undeveloped  on  the  femur.  The 
first  and  fifth  digits  of  the  pes  are  stouter  than  the  three  middle  ones. 
The  hind  limbs  are  not  capable  of  being  turned  forward  for  terrestrial 
locomotion. 

In  attempting  to  find  distinguishing  characters  in  the  skeletons  of 
fossil  pinnipeds,  especially  in  those  from  the  Antwerp  Basin,  Belgium, 
the  differences  in  the  humeri  and  femurs  have  been  found  to  be  fairly 
satisfactory,  inasmuch  as  most  of  the  described  species  are  very  im¬ 
perfectly  known.  The  vertebral  column  may  contain  diagnostic 
features,  but  the  material  available  has  but  little  significance  unless 
one  could  be  certain  of  the  position  in  the  column,  and  in  case  of  the 
Belgian  species,  whether  the  vertebrae  have  been  correctly  allocated  to 
the  species  in  question.  With  few  exceptions,  the  vertebrae  of  fossil 
seals  resemble  one  another  so  closely  that  accurate  indentification  is 
almost  impossible.  Fortunately,  the  writer  has  had  access  to  casts 
of  all  the  fossil  pinnipeds  from  the  Antwerp  Basin  described  by  Van 
Beneden.  These  casts  were  acquired  by  the  United  States  National 
Museum  many  years  ago  and  supplement  the  descriptions  and 
illustrations  given  by  Van  Beneden. 

Some  of  the  fossil  pelagic  mammals  which  have  been  collected  in 
the  diatomaceous  earth  deposits  at  Lompoc,  California,  are  well 
fossilized.  For  others  nothing  more  than  the  impressions  left  by  the 
bones  are  available  for  study.  Specimens  of  this  character  are 
usually  found  in  blocks  of  diatomaceous  earth  which  have  been 
quarried  in  the  usual  manner  by  the  workmen.  Blocks  which  contain 
large  fossils  frequently  split  at  the  level  of  the  specimen.  At  the 
time  the  specimen  is  first  exposed  many  of  the  bones  exhibit  their 
original  appearance,  but  after  a  few  hours’  exposure  they  commence 
to  disintegrate.  By  using  modern  methods,  an  experienced  collector 
could  preserve  the  bones  of  many  of  the  specimens  discovered.  The 
impressions  left  by  the  bones  in  the  soft  diatomaceous  earth,  however, 
are  often  remarkably  complete.  Fortunately,  many  new  advances 
have  been  made  in  recent  years  in  the  preparation  as  well  as  in  the 
methods  of  study  of  such  palaeontological  specimens.  In  the  past, 
impressions  of  the  original  bones  were  often  considered  to  be  in¬ 
adequate,  because  it  was  difficult  to  make  comparisons  between 
impressions  and  entire  bones.  By  taking  a  glue  mold  of  these  im¬ 
pressions,  it  is  possible  to  study  a  cast  which  reveals  the  peculiarities 
of  the  different  parts  of  the  skeleton. 

At  first  it  was  thought  that  many  of  the  differences  observed  in  the 
specimens  described  on  the  following  pages  were  of  specific  value,  but 


74  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast . 


closer  study  and  comparison  with  fur  seals  of  different  ages  has 
suggested  that  they  may  be  attributed  to  age  variation.  Specimens 
of  fur  seals  corresponding  in  size  to  these  fossils  have  been  selected 
in  order  to  facilitate  description  and  to  draw  attention  to  the  peculiar¬ 
ities  of  these  pinnipeds. 

The  writer  desires  to  acknowledge  his  indebtedness  to  Dr.  David 
Starr  Jordan  for  the  kindly  interest  which  he  has  shown  during  the 
progress  of  the  writer’s  studies,  as  well  as  for  the  opportunity  to 
describe  the  fossil  pelagic  mammals  obtained  through  his  efforts. 
Mr.  J.  W.  Lytle,  of  the  Museum  of  History,  Science,  and  Arts  of 
Los  Angeles,  prepared  the  casts  which  were  used  in  this  study. 

Pithanotaria  starri,  new  genus  and  species. 

Individual  I. 

Type  specimen. — Cat.  No.  11,  Museum  Stanford  University.  A  nearly  complete 
impression  of  the  skeleton  of  a  small  pinniped  showing  the  outlines  of  the  skull  and 
right  mandible,  the  right  fore  limb,  the  ribs,  and  the  vertebral  column  as  far  back  as  the 
ilium.  Impressions  of  two  sternebrae  and  some  of  the  bones  in  the  left  fore  limb  are 
also  present.  The  outlines  of  the  ilium  are  distinct;  the  remainder  of  the  innominate 
bone  is  missing.  The  femur,  patella,  and  proximal  ends  of  right  tibia  and  fibula  are 
present,  but  the  remainder  of  the  skeleton  occupied  an  adjoining  block  of  matrix. 

Type  locality. — The  Celite  Company’s  No.  9  quarry,  1.4  miles  south  of  the  inter¬ 
section  of  Ocean  Avenue  and  “C”  Street  in  the  town  of  Lompoc,  San  Bernardino 
County,  California. 

Horizon. — This  specimen  wTas  found  in  a  block  of  diatomaceous  earth  which  had 
been  quarried  on  the  property  of  the  Celite  Products  Company.  Mr.  Edward  B. 


Abbreviations:  A.,  atlas;  An.,  angle;  Ax.,  axis;  C.,  condyle;  C.  3  to  C.  7,  third  to  seventh  cervicals;  Cor.,  coronoic 
process,  D.  7  to  D.  15,  seventh  to  fifteenth  dorsals;  F.,  femur;  Fi.,  fibula  H.,  humerus;  II.,  ilium;  L.l  to  L.5,  firsl 
to  fifth  lumbars;  M.,  magnum;  Mn.,  manubrium;  P.,  patella;  R.,  radius;  Sc.,  scapula;  Scl.,  scapho-lunar;  St. 
sternebra;  T.,  tibia;  Trd.,  trapezoid;  Trm.,  trapezium;  U.,  ulna;  Ul.,  ulnare;  Un.,  unciform;  X,  either  the 
centrale  or  the  proximal  half  of  the  trapezoid;  I  to  V,  first  to  fifth  metacarpals. 


New  Pinnipeds  from  Vicinity  of  Lompoc,  California.  75 


Starr,  superintendent  of  the  company,  at  once  recognized  the  importance  of  the  im¬ 
pression  and  made  arrangements  with  Dr.  David  Starr  Jordan  to  forward  the  speci¬ 
men  to  Stanford  University.  The  fossil  pinniped  was  taken  from  a  level  approxi¬ 
mately  200  feet  above  the  base  of  the  deposit  of  diatomaceous  earth  which  at  this 
locality  attains  a  maximum  thickness  of  1,400  feet.  Sarmatian  or  Upper  Miocene. 

The  vertebral  column  of  this  fossil  pinniped,  judging  from  the  impressions  of  the 
vertebrae,  does  not  differ  to  any  marked  degree  from  that  of  a  two-year-old  Callo¬ 
rhinus  alascanus.  In  the  latter,  the  vertebral  column  consists  of  7  cervicals,  15  dorsals, 
5  lumbars,  3  sacrals,  and  10  caudals.  The  skeleton  of  a  two-year-old  male  Callorhinus 
alascanus  (Cat.  No.  14222,  U.  S.  Nat.  Mus.)  measures  1,000  mm.  in  length.  Although 
the  posterior  extremity  of  the  skeleton  of  the  fossil  pinniped  from  Lompoc  is  missing, 
the  total  length  hardly  exceeded  950  mm.  Following  the  curvature  of  the  vertebral 
column,  this  specimen  measures  770  mm.  from  the  tip  of  the  rostrum  to  the  anterior 
end  of  the  ilium. 

The  relationships  of  this  pinniped  appear  to  be  with  Callorhinus  and  Artocephalus. 
In  most  respects,  the  peculiarities  of  this  skeleton  are  quite  unlike  those  of  living  Pho- 
cidae,  although  the  radius  does  resemble  that  of  Phoca  in  its  general  outlines.  Briefly 
stated,  the  following  peculiarities  of  the  skeleton  of  this  fossil  pinniped  appear  to 
indicate  an  otarid  relationship.  The  slender  mandible  with  inflected  angle,  the 
presence  of  haplodont  molariform  teeth,  the  outline  and  almost  vertical  inclination  of 
the  transverse  processes  of  the  atlas,  a  scapula  with  a  large  prescapular  fossa,  a  humerus 
with  a  long  deltoid  crest  and  no  entepicondylar  foramen,  a  rather  stout  ulna  with 
styloid  process  directed  toward  the  radial  angle,  the  interdigitation  of  the  upper  end  of 
the  ulnare  between  the  styloid  process  of  the  ulna  and  the  epiphysis  of  the  radius,  the 
fact  that  the  upper  end  of  the  trapezoid  is  not  wedged  in  between  the  trapezium  and 
the  fused  scapho-lunar,  the  absence  of  modifications  for  nails  on  the  ungual  phalanges 
of  the  first  and  fifth  digits  in  the  manus  and  pes,  and  the  possession  of  a  slender  ilium 
of  the  typical  otarid  type. 

Skull. 

From  the  skull  of  a  two-year-old  Callorhinus  alascanus ,  the  most  apparent  dis¬ 
tinctions  are  in  the  greater  depth  of  the  brain-case,  the  lesser  depth  of  the  rostrum,  and 
the  more  convex  curvature  of  the  brain-case  as  viewed  from  the  side.  Some  of  these 
differences  may  not  be  real  and  possibly  may  be  attributed  to  crushing.  The  rostrum 
is  relatively  short,  the  interorbital  region  flattened,  and  the  brain-case  arched.  As 
regards  the  rostrum,  this  fossil  skull  differs  from  those  of  living  otarids,  with  the 
exception  of  females  of  Arctocephalus  and  Zalophus,  in  its  length  and  depth.  The 
rostrum  of  the  skull  of  a  young  Callorhinus  is  relatively  shorter  and  deeper.  A  skull 
of  a  young  Arctocephalus  was  not  available  for  comparison.  The  dorsal  outline  of  the 
skull  of  this  fossil  otarid  is  quite  different  from  those  of  young  individuals  of  Callorhinus 
and  Zalophus;  the  brain-case  also  is  relatively  deeper  than  that  of  a  rather  young 
Otaria  byronia  from  Peru.  A  small  postorbital  process  seems  to  be  present.  The 
postorbital  constriction  is  not  as  well  marked  as  in  Callorhinus.  Hence  the  brain-case 
probably  was  not  as  quadrangular  in  outline  as  in  the  latter.  The  antero-lateral  angle 
of  the  brain-case  varies  in  its  sharpness  with  age  and  sex;  these  angles  are  more  con¬ 
spicuous  in  a  two-year-old  male  than  in  an  old  bull  Callorhinus.  The  orbit  of  this  skull 
is  smaller  than  that  of  the  fur  seal.  Sagittal  and  occipital  crests  are  well  developed  in 
old  bull  fur  seals,  but  are  absent  on  skulls  of  young  individuals.  No  sagittal  crest  was 
present  on  this  fossil  skull.  The  parietal  bone  appears  to  correspond  in  curvature  and 
proportions  with  that  of  a  young  Callorhinus.  The  anterior  and  posterior  nares  open 
in  the  same  position  as  in  the  fur  seal.  Some  of  the  more  conspicuous  structures  of  the 
skull  are  not  indicated  very  clearly  in  the  impression.  Of  these,  the  zygomatic  process, 
the  auditory  bulla,  and  occipital  condyle  are  the  most  important. 

In  size  and  proportions  this  right  mandible  also  agrees  with  that  of  a  two-year-old 
Callorhinus  alascanus.  The  mandible  is  slender,  with  inflected  angle  and  narrow  con- 


76  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


dyle.  The  interval  between  the  angle  and  the  condyle  is  about  the  same  as  in  Callo- 
rhinus.  The  impression  of  the  upper  portion  of  the  coronoid  process  has  been  obliter¬ 
ated,  but  the  curvature  of  the  anterior  border  at  the  base  corresponds  to  that  of  a 
young  fur  seal. 

The  dentition  of  this  skull  agrees  with  that  of  a  two-year  old  Callorhinus.  As  in 
the  fur  seal,  the  outer  upper  incisor  is  larger  than  the  others  and  caniniform;  the 
impressions  of  the  lower  incisors  are  indistinct.  The  canines  are  large  and  sharply 
pointed;  the  lower  canine  is  slightly  curved,  but  the  upper  is  nearly  straight.  As 
in  Callorhinus,  the  premolars  are  not  sharply  differentiated  from  the  molars.  All  of 
the  molariform  teeth  have  a  simple  laterally  compressed  crown  and  poorly  defined 
cingulum.  No  accessory  cusps  were  present,  or  at  least  none  are  indicated  in  the  im¬ 
pressions  of  the  upper  molariform  series.  The  impression  of  the  fifth  upper  molari¬ 
form  tooth  is  not  as  distinct  as  the  others,  and  it  is  possible  that  it  may  have  had  a 
small  posterior  accessory  cusp.  Impressions  of  5  molariform  teeth  are  present  in  the 
upper  jaw.  Some  of  the  molariform  teeth  are  missing  from  the  mandible,  as  only  3 
are  present. 


Table  1. — Comparative  measurements  of  the  skulls  (in  millimeters) . 


Pithanotaria  starri, 
Lompoc,  California. 
Cat.  No.  11,  Mus., 
Stanford  University. 

Callorhinus  alascanus , 
St.  Paul  Island,  Alas¬ 
ka,  2  year  old  cT.  Cat. 
No.  14222  U.  S.  Nat. 
Mus. 

Condylobasal  length  of  skull . 

154 

178 

Occipito-nasal  length  of  skull . 

X 

129 

Vertical  depth  of  brain-case  at  apex  supra- 
occipital . 

76 

67.5 

Vertical  depth  of  rostrum  at  base  of  nasals. . . . 

38 

45 

Zygomatic  breadth  of  skull . 

X 

103.4 

Mastoid  breadth  of  skull . 

X 

88 

Breadth  across  occipital  condyles  (outside 

measurement) . . 

X 

50.5 

Length  of  palate  (to  median  notch) . 

X 

61 

Base  of  pterygoid  to  extremity  of  premaxilla 

X 

105 

Interorbital  constriction . 

X 

23.5 

Postorbital  constriction . 

X 

33.5 

Length  of  upper  molariform  series . 

»  41 

*45 

Length  of  right  mandible  (extremity  to  con¬ 
dyle)  . 

112 

114 

Depth  of  right  mandible  at  coronoid  process 
(angle  to  tip) . 

X 

34.6 

Depth  of  right  mandible  at  level  of  last  molar 

15 

15.5 

Depth  of  right  mandible  at  level  of  third 
premolar . 

18.5 

21 

Length  of  lower  molariform  series . 

X 

35.2 

1  Five  teeth.  2  Six  teeth. 


Fore  Limb. 

The  impression  of  the  right  fore  limb  is  remarkably  complete.  Even  the  ungual 
phalanges  are  represented.  The  total  length  of  the  fore  limb  in  its  present  position 
as  measured  from  the  vertebral  margin  of  the  scapula  to  the  distal  end  of  the  first 
phalange  of  the  first  digit  is  370  mm.  The  same  measurement  for  the  fore  limb  of  a 
two-year-old  Callorhinus  alascanus  is  470  mm.  The  illustration  (text-fig.  1)  which 
accompanies  this  description  represents  the  various  elements  in  the  position  in  which 
they  occur  on  the  slab  of  diatomaceous  earth. 


New  Pinnipeds  from  Vicinity  of  Lompoc ,  California.  77 


Scapula. 

None  of  the  living  Holarctic  phocids,  so  far  as  can  be  judged  by  these  impres¬ 
sions,  possess  a  scapula  of  this  type.  The  scapula  of  Monachus  tropicalis  bears  a  slight 
resemblance  to  that  of  this  fossil  otarid,  but  the  position  of  the  spine  is  quite  different. 
The  coracoid  or  anterior  border  of  this  fossil  scapula  does  not  merge  into  the  supra¬ 
scapular  border  in  a  more  or  less  regular  curve  as  in  Phoca  vitulina;1  the  outlines  of 
the  blade  as  well  as  the  size  and  position  of  the  fossae  resemble  the  scapula  of  a  two- 
year-old  Callorhinus  alascanus  very  closely.  The  prescapular  fossa  is  relatively  large, 
the  postscapular  portion  is  elongated,  and  the  spine  extends  about  seven-ninths  the 
depth  of  the  blade.  There  is  no  indication  of  a  hook-like  process  at  the  inferior  angle. 
The  scapula  of  this  fossil  otarid  is  not  as  deep  as  that  of  a  young  Callorhinus  and  the 
inferior  angle  is  prolonged  further  backward.  In  front  of  the  spine  the  external 
surface  of  the  scapula  is  relatively  flat  and  to  this  was  attached  the  deltoid  muscle. 
Further  forward  and  along  the  coracoid  margin  the  scapula  is  depressed  as  in  Callo¬ 
rhinus  alascanus.  A  muscle  which  assists  the  deltoid  in  abducting  the  humerus  arises 
in  this  area.  Phoca  vitulina  and  Phoca  sibirica  possess  falciform  scapulae  which 
resemble  each  other,  as  well  as  other  species  of  the  genus  Phoca  in  a  general  way,  and 
may  be  taken  as  representative  of  the  type  characteristic  of  this  genus.  In  these 
species  the  coracoid  border  curves  forward  and  upward  from  the  neck  to  the  supra¬ 
scapular  border  and  passes  imperceptibly  into  the  latter.  A  well-developed  hook-like 
process  is  present  below  the  inferior  angle.  The  coracoid  border  is  not  depressed 
below  the  area  for  attachment  of  the  deltoid  muscle,  the  prescapular  fossa  is  not 
considerably  larger  than  the  postscapular  fossa,  and  the  spine  arises  near  the  middle 
of  the  blade.  Hence  the  scapula  agrees  in  all  particulars  with  those  of  otarids  and 
differs  from  the  phocids  in  all  the  features  enumerated  above. 

Humerus. 

The  impression  of  the  external  face  of  the  right  humerus  reveals  the  curvature 
of  the  shaft,  the  proportions  of  the  head  and  deltoid  crest,  the  shape  of  the  lower  troch¬ 
lear  portion,  and  the  outline  of  the  supinator  ridge.  The  lesser  tuberosity  and  inter¬ 
nal  condyle  alone  are  missing  to  give  a  complete  picture  of  this  humerus.  Compared 
with  the  corresponding  element  of  Prophoca  proxima,2  it  is  somewhat  smaller  and 
agrees  very  closely  in  general  form,  except  for  the  more  pronounced  over-rolling  of 
the  deltoid  crest  on  the  external  margin,  the  more  flaring  supinator  ridge,  and  the 
absence  of  an  entepicondylar  foramen.  The  supinator  ridge  is  thin  and  of  approxi¬ 
mately  the  same  length  as  in  Callorhinus.  Comparisons  made  between  the  cast 
of  the  left  humerus  of  Prophoca  proxima  and  the  same  element  in  skeletons  of  living 
phocids  revealed  some  well-marked  differences.  The  deltoid  crest  is  exceptionally 
long  as  compared  with  the  same  structure  on  a  humerus  of  Phoca  vitulina,  and  the 
upper  portion  of  the  supinator  ridge  is  directed  backward  in  a  plane  parallel  to  that 
of  the  deltoid  crest.  Consequently,  the  distal  portion  of  the  humerus  was  somewhat 
narrower  than  that  of  Phoca  vitulina,  on  which  the  supinator  ridge  is  directed  more 
outward  than  backward.  In  the  direction  and  length  of  the  supinator  ridge  and  in 
the  large  size  of  the  capitulum,  the  humerus  of  Pithanotaria  starri  resembles  that  of  a 
two-year-old  Callorhinus  alascanus  more  closely  than  any  of  the  previously  described 
fossil  phocids.  This  humerus  is  also  larger  than  that  of  Phoca  vindobonensis ;3  the 
large  size  of  the  head  and  the  flaring  margin  of  the  deltoid  crest  further  distinguish 

1  H.  M.  D.  Blainville,  Osteographie  ou  description  iconographique,  Paris,  fasc.,  Phoca, 
plate  2,  1843. 

2  P.  J.  Van  Beneden,  Description  des  ossements  fossiles  des  environs  d’ Anvers — Premiere 
Partie,  Pinnipedes  ou  Amphiterien3,  Annales  du  Mus.  d’hist.  nat.  de  Belgique,  Bruxelles, 
tome  1,  plate  18,  figs.  12,  13,  1877. 

3  F.  Toula.,  Phoca  vindobonensis  n.  sp.  von  Nussdorf,  in  Wien.  Beitrage  z.  Palaont.  u.  Geol. 
Osterreich-Ungarns  u.d.  Orients,  Wien  und  Leipzig,  Bd.  11,  heft  2,  pp.  47-70,  plates  9  to  11, 
1S97. 


78  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


this  pinniped  from  the  Vindobonian  phocid  of  the  Vienna  basin.  In  Prophoca  proxima 
the  depth  of  the  humerus  through  the  coronoid  fossa  is  somewhat  greater  than  in  this 
pinniped  from  Lompoc.  In  a  two-year-old  Callorhinus  alascanus  the  depth  of  the 
humerus  at  this  point  is  approximately  the  same  as  in  this  fossil  humerus.  The  curva¬ 
ture  of  the  anterior  and  posterior  borders  of  the  shaft  also  agree  with  Callorhinus. 
Leptophoca  lenis 1  from  the  Calvert  formation  of  Maryland  has  a  humerus  with  a  shorter 
deltoid  crest,  longer  shaft,  and  less  flaring  supinator  ridge.  The  humerus  of  Pho- 
canella  pumila 2  has  a  short  deltoid  crest  which  corresponds  in  a  general  way  with  that 
of  Phoca  vitulina  and  Phoca  hispida,  but  the  head  is  smaller  and  the  shaft  slenderer 
than  in  this  fossil  otarid. 

Radius. 

On  comparing  the  external  views  of  this  radius  and  those  of  Phoca  vitulina  and 
Phoca  hispida,  it  is  interesting  to  note  how  closely  they  resemble  one  another  in 
general  outlines.  The  head  is  somewhat  wider  than  the  neck  in  contrast  to  the  more 
uniform  proportions  of  the  proximal  end  of  the  left  radius  of  Prophoca  proxima.  The 
posterior  border  of  the  radius  is  rather  evenly  curved,  but  the  curvature  of  the  anterior 
border  is  not  as  regular.  Commencing  at  the  neck,  the  curvature  of  the  anterior 
border  at  first  is  gradual,  but  below  the  middle  the  expansion  becomes  very  pro¬ 
nounced  and  imparts  a  characteristic  outline  to  this  element.  The  curvature  of  the 
anterior  border  of  the  radius  of  Callorhinus  alascanus  as  viewed  from  the  side  is  quite 
different  from  this  type,  being  irregularly  biconcave;  the  shaft  expands  rather  suddenly 
above  the  rugosity  which  marks  the  insertion  of  the  tendon  and  flexor  muscle  of  the 
wrist,  and  below  this  point  the  border  gradually  curves  forward  to  the  widest  part 
of  the  radius,  which  is  just  above  the  insertion  of  the  flexor  muscle  of  the  elbow  joint. 
As  in  living  pinnipeds,  the  lower  portion  of  the  radius  of  Pithanotaria  starri  is  flat¬ 
tened  from  side  to  side.  On  the  radius  of  Phoca  vitulina  and  other  living  phocids, 
there  is  a  well-defined  notch  on  the  anterior  border  which  extends  obliquely  upward 
and  backward  between  the  shaft  and  the  distal  epiphysis  for  the  insertion  of  the  flexor 
muscle  of  the  elbow  joint.  There  is  a  poorly  defined  groove  for  this  muscle  near  the 
same  point  on  the  left  radius  of  Prophoca  proxima.  Close  scrutiny  of  the  impression 
of  the  right  radius  of  this  fossil  otarid  convinced  the  writer  that  the  notch,  if  present, 
was  very  shallow,  although  the  surface  may  have  been  slightly  grooved.  The  distal 
extremity  of  the  radius,  including  the  epiphysis,  resembles  the  same  element  in  the 
fore  limb  of  a  two-year-old  Callorhinus  alascanus  more  closely  than  Phoca.  There  are 
no  ridges  in  the  impression  which  would  indicate  the  presence  of  grooves  for  tendons 
and  muscles  as  in  Phoca,  and  the  entire  surface  in  this  region  is  relatively  smooth,  as 
in  Callorhinus.  In  addition  to  the  presence  of  grooves  for  tendons  and  muscles  on 
the  external  surface  of  the  distal  extremity  of  the  radius  of  Phoca  vindobonensis,  there 
are  other  differences  which  have  a  more  important  bearing  upon  its  relationships  with 
the  pinniped  from  Lompoc.  Among  these  peculiarities,  the  oblique  curvature  of  the 
anterior  face  of  the  shaft  and  the  wide  neck  of  the  radius  of  the  Vienna  phocid  are  the 
most  obvious. 

Ulna. 

In  its  general  form,  the  ulna  undoubtedly  was  very  similar  to  that  of  a  young 
Callorhinus  alascanus.  The  right  ulna  of  this  otarid  differs  considerably  from  that 
of  Phoca  vindobonensis  and  those  of  living  phocids  in  several  respects.  The  most 
apparent  differences  are  the  curvature  of  the  posterior  margin  of  the  olecranon  process, 
the  greater  width  of  the  distal  end  of  the  shaft,  and  the  shape  and  position  of  the 
styloid  process.  In  the  width  of  the  distal  end  of  the  shaft,  the  position  of  the  styloid 
process,  and  the  extent  of  the  facets  for  the  radius  and  ulnare,  this  ulna  resembles 

1  F.  W.  True,  Description  of  a  new  genus  and  species  of  fossil  seal  from  the  Miocene  of 
Maryland,  Proc.  U.  S.  Nat.  Mus.,  vol.  30,  Publ.  1475,  pp.  835-840,  plates  75,  76,  1906. 

2  P.  J.  Van  Beneden,  Op.  cit.,  plate  14,  figs.  1  to  4,  1877. 


New  Pinnipeds  from  Vicinity  of  Lompoc ,  California.  79 


that  of  a  two-year-old  Callorhinus.  The  greater  sigmoid  cavity  on  the  anterior  face 
of  the  ulna  for  articulation  with  the  trochlea  of  the  humerus  is  characterized  by  an 
evenly  concave  curve;  its  proximo-distal  diameter  is  about  equal  to  that  of  a  young 
fur  seal.  The  articular  surface  of  the  greater  sigmoid  cavity  is  continuous  with  the 
lesser  sigmoid  cavity  which  articulates  with  the  head  of  the  radius.  In  position  and 
size  this  facet  also  agrees  with  that  of  a  young  fur  seal.  The  external  surface  of  the 
olecranon  process  appears  to  have  been  flattened,  while  in  Callorhinus  there  is  a  well- 
defined  triangular  concavity  for  the  insertion  of  the  extensor  muscle  of  the  elbow 
joint.  The  shaft  of  the  ulna  is  relatively  stout. 


Table  2. — Comparative  measurements  of  the  bones  of  the  fore  limb  (in  millimeters). 


Pithanotaria 
starri,  Lompoc, 
California.  Cat. 
No.  11,  Mus., 
Stanford 
University. 

Callorhinus  alas* 
canus,  St.  Paul 
Island,  Alaska. 
2-year-old  d- 
Cat.  No.  14222, 
U.  S.  Nat.  Mus. 

Scapula : 

Anterior  angle  to  inferior  angle . 

143.5 

141.5 

Vertebral  margin  to  glenoid  concavity . 

82.5 

118.5 

Anterior  margin  of  neck  to  inferior  angle . 

120 

118 

Breadth  of  neck . 

27 

24 

Humerus : 

Head  to  capitulum . . 

106.5 

105 

Greater  tuberosity  to  crest  of  inner  trochlea . 

X 

118.5 

Breadth  of  humerus  from  lesser  tuberosity  to  head 

X 

39.5 

Breadth  of  humerus  from  inner  to  external  condyle. 

X 

41 

Greatest  depth  of  humerus  at  deltoid  crest . 

32 

32 

Least  thickness  of  humerus  at  coronoid  fossa . 

11 

12 

Radius: 

Greatest  length  of  radius . 

90.5 

118 

Greatest  breadth  of  radius  at  proximal  end . 

23 

19 

Greatest  breadth  of  radius  at  distal  end . 

32 

34 

Breadth  of  radius  across  tubercle . 

X 

11.2 

Ulna: 

Greatest  length  of  ulna . . . 

111 

145.5 

Inferior  margin  of  sigmoid  cavity  to  superior  mar- 

gin  of  olecranon  process . 

32 

45 

Breadth  of  olecranon  process  at  inferior  margin 

of  greater  sigmoid  cavity . 

21 

25 

Greatest  breadth  of  ulna  at  level  of  lower  facet 

for  radius . 

19.2 

16.5 

Carpus. 

The  structure  of  the  carpus  appears  to  be  rather  unusual  in  several  respects.  The 
bones  are  unequal  in  size;  the  magnum  and  ulnare  are  nearly  equal  in  the  propor¬ 
tions  of  their  anterior  faces;  the  trapezium  appears  to  be  relatively  small.  There  are 
two  impressions  in  the  area  where  the  trapezoid  should  occur,  and  if  they  represent  the 
upper  and  lower  portions  of  the  anterior  surface,  then  this  element  was  traversed 
mesially  by  a  horizontal  groove  or  depression.  The  trapezoid  would  then  be  almost 
as  large  as  the  trapezium.  In  these  respects  the  relations  of  these  carpal  bones  ap¬ 
proach  the  conditions  existing  in  Callorhinus  alascanus.  As  viewed  from  in  front, 
the  trapezoid  in  the  carpus  of  Phoca  vitulina  and  Phoca  fasciata  is  relatively  slender 
and  the  upper  extremity  is  interposed  between  the  trapezium  and  the  fused  scapho- 
lunar-centrale.  It  is  barely  possible  that  the  upper  depression  (text-fig.  1,  X)  may 
represent  the  centrale.  In  that  case  the  larger  element,  which  articulates  with  the 
radius,  would  consist  of  the  scaphoid  and  lunar  alone.  The  presence  of  a  wholly  con¬ 
solidated  scapho-lunar-centrale  in  the  Pinnipedia  has  been  regarded  as  a  highly  im- 


80  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


portant  character.  This  fusion  has  been  held  to  preclude  their  derivation  from  a  form 
which  possesses  these  as  separate  elements.  No  conclusive  evidence  that  this  charac¬ 
ter  was  acquired  during  the  aquatic  adaptation  of  the  group  has  been  presented  up  to 
the  present  time.  Hence  it  is  to  be  regretted  that  the  actual  bones  of  this  carpus  are 
not  available.  The  scaphoid  and  lunar  have  consolidated,  and  the  only  dubious  point 
is  the  interpretation  of  the  above-mentioned  depression.  If  it  does  represent  the 
centrale,  then  aquatic  adaptation  in  this  group  has  resulted  in  the  fusion  of  the  cen- 
trale  with  the  scapho-lunar.  The  question  of  the  consolidation  of  the  scaphoid  and 
lunar  would  then  await  the  discovery  of  some  earlier  form.  At  present  the  evidence 
does  not  appear  to  be  very  conclusive.  Under  either  interpretation  the  trapezoid 
differs  in  position  and  proportions  from  the  same  element  in  the  carpus  of  Phoca.  The 
displacement  of  some  of  the  carpal  bones  is  also  unfortunate,  for  it  is  difficult  to  recon- 
truct  the  carpus  from  impressions  of  the  elements.  The  ulnare  is  much  smaller  than 
the  same  element  in  the  carpus  of  Phoca ,  but  it  does  resemble  that  of  Callorhinus. 
Judging  from  the  impression,  the  upper  end  of  the  ulnare  may  have  been  interposed 
between  the  epiphysis  of  the  radius  and  the  styloid  process  of  the  ulna  as  in  the  car¬ 
pus  of  Callorhinus.  In  the  latter,  the  articular  facets  for  the  radius  and  ulna  are  on 
the  external  and  internal  faces  of  the  ulnare.  In  Phoca  vitulina  the  facet  on  the  ulnare 
for  articulation  with  the  styloid  process  of  the  ulna  is  on  the  proximal  face.  The 
ulnare  of  this  fossil  otarid  is  rather  small  and  the  styloid  process  of  the  ulna  rather 
large.  The  displacement  of  the  unciform  probably  took  place  at  the  time  the  head 
of  the  fifth  metacarpal  was  thrust  upward  into  the  carpus.  The  large  size  of  the 
unciform  is  most  unusual  for  a  pinniped.  It  is  as  large  as  or  larger  than  the  trapezium. 

Measurements  of  the  bones  of  the  carpus  {in  millimeters). 


Maximum  width  of  the  scapho-lunar-centrale  (?) .  28.2 

Maximum  depth  of  the  scapho-lunar-centrale  (?) .  13 

Maximum  width  of  the  trapezium .  10.5 

Maximum  depth  of  the  trapezium .  15.8 

Maximum  depth  of  the  trapezoid .  13 

Maximum  width  of  the  magnum .  12.2 

Maximum  width  of  the  ulnare .  7.8 

Maximum  depth  of  the  ulnare . 12.5 

Maximum  width  of  the  unciform .  18.2 

Maximum  depth  of  the  unciform .  12.3 


Digits. 

In  structure  the  broad  flat  flipper  of  this  fossil  otarid  does  not  differ  in  any  essen¬ 
tial  detail  from  that  of  a  two-year-old  Callorhinus  alascanus.  The  relative  lengths  and 
proportions  of  the  first  and  fifth  digits  are  remarkably  close.  The  ungual  phalanges 
were  rather  short,  broad,  and  bluntly  pointed.  In  the  living  fur  seal,  the  first  digit 
consists  of  a  metacarpal  and  two  phalanges;  the  other  digits  have  an  additional 
phalange.  Unfortunately,  the  impressions  of  the  first  and  fifth  digits  are  not  com¬ 
plete.  The  impressions  of  the  first  four  digits  correspond  to  their  normal  position; 
the  fifth  has  been  twisted.  This  shifting  of  the  fifth  digit  may  have  caused  the  disas- 
sociation  of  some  of  the  carpal  bones. 

The  first  metacarpal  is  larger  than  all  the  others,  both  in  respect  to  length  and  rela¬ 
tive  proportions.  The  radial  angle  of  the  proximal  end  of  this  metacarpal  projects 
beyond  the  level  of  the  ulnar  angle.  The  distal  extremity  of  this  metacarpal  is  slightly 
expanded.  The  second  metacarpal  is  rather  slender,  with  no  evident  disparity  in  size 
between  the  shaft  and  the  proximal  end.  The  head  of  the  third  metacarpal  is  notice¬ 
ably  expanded.  The  fourth  and  fifth  metacarpals  are  slightly  shorter  and  resemble 
the  same  element  in  the  flipper  of  a  young  Callorhinus  alascanus.  The  first  phalange 
of  the  first  digit  is  broader  and  longer  than  any  of  the  others.  All  of  the  second 
phalanges  are  slender  and  taper  toward  the  distal  end.  The  ungual  phalanges  of  the 
second,  third,  and  fourth  digits  are  modified  to  support  nails. 


New  Pinnipeds  from  Vicinity  of  Lompoc ,  California.  81 


Table  3. — Comparative  measurements  of  the  greatest  length  of  metacarpals  and  phalanges 

(in  millimeters) . 


Pithanotaria  starri, 
Lompoc,  California. 
Cat.  No.  11,  Mus. 
Stanford  University. 

Callorhinus  alascanus, 
St.  Paul  Island,  Alas¬ 
ka,  2-year-old  <+. 
Cat.  No.  14222,  U.  S. 
Nat.  Mus. 

First  metacarpal . 

55.2 

67.4 

First  phalange  of  first  digit . 

45  + 

64.5 

Second  phalange  of  first  digit . 

X 

25.5 

Second  metacarpal . 

38.2 

48 

First  phalange  of  second  digit . 

32 

47 

Second  phalange  of  second  digit . 

25 

38 

Third  phalange  of  second  digit . 

10 

X 

Third-metacarpal . 

34.6 

44.5 

First  phalange  of  third  digit . 

25.5 

37 

Second  phalange  of  third  digit . 

20.4 

30 

Third  phalange  of  third  digit . 

9.8 

X 

Fourth  metacarpal . 

30.8 

37.5 

First  phalange  of  fourth  digit . 

25 

27.5 

Second  phalange  of  fourth  digit . 

16.5 

22.4 

Third  phalange  of  fourth  digit . 

8.5 

X 

Fifth  metacarpal . 

32 

36.6 

First  phalange  of  fifth  digit . 

23.5 

25.3 

Second  phalange  of  fifth  digit . 

X 

6.5 

Third  phalange  of  fifth  digit . 

9 

X 

Cervical  Vertebrae. 

Very  little  can  be  said  concerning  the  atlas  of  this  pinniped  except  that  it  agrees 
rather  closely  with  that  of  the  living  Callorhinus  alascanus.  The  impression  of  the 
atlas  is  not  complete,  as  only  a  portion  of  the  posterior  surface  is  represented;  the  right 
lateral  margin  is  nearest  to  the  skull.  In  size  it  was  somewhat  smaller  than  the  atlas 
of  a  tw~o-year-old  Callorhinus  alascanus  (Cat.  No.  14222  U.  S.  Nat.  Mus.);  the  greatest 
depth  of  the  neural  canal  of  the  last-mentioned  vertebra  is  23.5  mm.  and  the  breadth 
across  the  transverse  processes  is  73.5  mm.  Turning  again  to  this  fossil  atlas,  it  ap¬ 
pears  that  the  neural  canal  measured  18  mm.  in  depth  and  the  estimated  breadth  across 
the  transverse  processes  is  60  mm.  The  size  and  curvature  of  the  neural  canal  are  very 
clearly  indicated.  The  posterior  articular  facets  also  were  similar  in  size  and  propor¬ 
tions  to  those  of  a  young  fur-seal  atlas.  This  impression  does  not  include  the  left 
transverse  process  and  only  a  portion  of  the  left  posterior  articular  facet  is  represented. 
The  peculiarities  of  the  anterior  surface  of  this  atlas  are  unknown. 

A  lateral  view  of  the  axis  is  afforded  by  the  impression  of  this  element.  The  neural 
spine  and  odontoid  process  are  fairly  well  defined;  the  right  anterior  articular  facet 
and  the  right  postzygapophysis  are  more  or  less  clearly  outlined.  This  axis  does 
not  appear  to  differ  structurally  from  that  of  a  two-year-old  Callorhinus  alascanus. 

Judging  from  their  impressions,  the  remaining  cervical  vertebrae  also  correspond 
to  those  of  a  young  fur  seal,  although  they  are  slightly  smaller.  The  proportions  of 
the  pre-  and  post-zygapophyses  can  be  determined  from  the  impressions  of  the  fourth 
and  fifth  cervicals,  and  the  position  of  the  upper  and  lower  transverse  processes  are 
indicated  on  the  third,  fourth,  and  fifth  cervicals.  The  impressions  of  the  last  three 
cervicals  are  not  as  complete  as  those  of  the  first  four. 

Dorsal  Vertebrae. 

Analysis  of  the  impressions  and  comparison  of  the  size  of  the  vertebrae  with  those 
of  a  two-year-old  Callorhinus  alascanus  lead  to  the  conclusion  that  15  dorsal  vertebrae 
were  present  in  this  skeleton.  There  are  impressions  of  9  dorsals  posterior  to  the 
scapula.  Impressions  of  3  dorsal  vertebrae  are  present  on  the  inner  face  of  the  scapula. 


82  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


The  position  of  the  anterior  dorsals  and  the  intervals  which  separate  them  show  that 
these  vertebrae  were  disarticulated  before  the  skeleton  was  covered  with  sediments. 
The  manubrium  or  anterior  sternebra  is  in  contact  with  the  sixth  and  seventh  cervicals 
and  the  impression  of  the  neural  spine  of  the  sixth  cervical  passes  beneath  the  coracoid 
border  of  the  scapula.  This  confirms  the  severance  of  the  vertebral  column  posterior 
to  the  cervical  series.  The  dorsal  vertebrae  average  smaller  than  those  of  a  two-year- 
old  Caliurhinus  alascanus. 

The  following  comments  on  the  dorsal  series  of  this  skeleton  are  based  upon  com¬ 
parisons  between  the  impressions  taken  from  the  same  series  of  a  two-year-old  Callo- 
rhinus  alascanus  skeleton  and  those  on  this  slab  of  diatomaceous  earth.  Inasmuch  as 
no  marked  differences  could  be  observed,  the  peculiarities  of  these  vertebrae  have  been 
interpreted  from  the  Callorhinus  skeleton.  The  metapophyses  appear  to  have  been 
low  and  rounded.  Beginning  with  the  fifth  in  the  dorsal  series  of  Callorhinus ,  the  an¬ 
terior  angle  of  the  metapophysis  becomes  more  pronounced.  As  we  go  backward  along 
the  series  as  far  as  the  eleventh  dorsal,  there  is  relatively  little  change  in  the  shape  of 
this  angle,  but  on  the  twelfth  it  moves  inward  and  assumes  a  more  oblique  position. 
On  the  thirteenth  the  metapophysis  contributes  the  outer  surface  of  the  prezygapo- 
physial  facet.  From  this  dorsal  to  the  end  of  the  series  the  metapophysis  is  con¬ 
tinuous  with  the  prezygapophysis.  There  is  a  distinct  anapophysis  on  the  thir¬ 
teenth  dorsal,  and  it  increases  slightly  in  size  on  the  fourteenth  and  fifteenth.  It  is 
absent  on  the  lumbar  vertebrae.  The  neural  spines  of  the  anterior  dorsal  vertebrae 
were  high;  those  on  the  posterior  dorsals  were  considerably  lower,  as  in  Callorhinus. 
The  centra  increase  in  length  toward  the  end  of  the  dorsal  series. 

In  a  skeleton  of  a  two-year-old  Callorhinus  alascanus,  the  facets  for  the  tubercula 
of  the  ribs  are  cup-shaped  on  the  first  and  second  dorsals  and  flattened  on  the  third 
to  fifteenth.  Demifacets  for  the  capitula  are  present  on  the  centra  of  the  third  to 
eleventh  dorsals  inclusive.  The  impressions  of  the  transverse  processes  are  distinct, 
but  the  position  and  peculiarities  of  the  facets  for  the  ribs  are  not  sharply  defined.  On 
the  whole  the  dorsal  series  appears  to  agree  very  closely  writh  that  of  the  young  fur  seal. 
The  impression  of  the  centrum  of  the  seventh  dorsal  of  this  fossil  otarid  measures  15 
mm.  in  length  and  the  vertical  distance  from  the  tip  of  the  spine  to  the  inferior  face  of 
the  centrum  is  36.5  mm. 

Lumbar  Vertebrae. 

Five  lumbar  vertebrae  were  present  in  this  skeleton.  The  centra  of  the  first  and 
second  lumbar  vertebrae  are  slightly  longer  than  the  others  and  the  fifth  lumbar  has  a 
longer  transverse  process  than  the  first.  The  metapophyses  were  high  and  projected 
forward  and  outward.  The  neural  spines  are  lower  than  those  of  the  posterior  dorsals. 
All  five  of  these  lumbars  wTere  of  the  Callorhinus  type. 

Ribs. 

Impressions  of  more  than  17  ribs  are  present,  several  being  nearly  complete,  but  it 
is  a  difficult  matter  to  determine  how  many  belong  on  the  right  side.  Four  or  five  of 
the  anterior  ribs,  which  normally  underlie  the  scapula,  are  certainly  missing.  Only 
one  of  these  ribs  has  left  its  impression  on  the  inner  face  of  the  scapula.  Some  evidence 
of  wave  action  is  afforded  by  the  abnormal  position  of  the  left  scapula,  the  impression 
of  the  internal  face  of  this  bone  being  situated  above  the  vertebral  column.  Otherwise, 
the  bones  in  the  skeleton  rest  in  the  position  of  a  seal  lying  on  its  side.  All  of  the  ribs 
are  rather  long  and  slender,  with  expanded  extremities.  Well-developed  tubercula 
were  present  on  the  anterior  ribs,  but  the  length  of  the  neck  and  the  size  of  the  capitu- 
lum  are  not  shown  in  any  of  the  rib  impressions.  All  of  these  ribs  appear  to  be  mod¬ 
erately  curved  from  end  to  end.  Eleven  vertebral  ribs  are  connected  wdth  the  sterne- 
brae  by  cartilaginous  sternal  ribs  In  the  skeleton  of  a  young  Callorhinus  alascanus. 


New  Pinnipeds  from  Vicinity  of  Lompoc ,  California.  83 


Sternebrae. 

In  the  living  Ofcariidae,  the  sternebrae  are  not  fused  together  to  form  three  elements, 
but  remain  distinct.  There  are  9  sternebrae  in  the  sternum  of  Callorhinus  and  Arcto- 
cephalus.  Impressions  of  two  sternebrae  are  shown  on  this  slab  of  diatomaceous  earth 
and  one  of  these  is  the  manubrium.  The  latter  is  long  and  slender  and  measures 
67  mm.  in  length,  exceeding  that  of  a  two-year-old  Callorhinus  alascanus.  The  other 
sternebra  measures  26  mm.  in  length  and  its  proportions  correspond  with  those  of  the 
fur  seal. 

Pelvis. 

Of  the  pelvis,  only  the  impression  of  the  anterior  end  of  the  right  ilium  appears 
to  be  represented.  This  element  was  slender,  as  in  the  living  otarids,  with  the  anterior 
extremity  curved  slightly  outward.  In  proportions  and  length  the  ilium  of  this  fossil 
otarid  is  practically  indistinguishable  from  that  of  a  two-year-old  Callorhinus  alas¬ 
canus.  The  length  of  the  ilium  of  this  fossil  otarid  is  about  50  mm.,  while  that  of  a 
two-year-old  fur  seal  measures  50.5  mm.  It  articulated  with  the  first  and  second 
saerals,  but  furnishes  little  additional  information  on  the  structure  of  the  pelvic 
girdle  of  these  Miocene  otarids.  This  imperfectly  preserved  pelvic  girdle  does  show 
that  before  the  close  of  the  Miocene  period  the  otarids  had  already  acquired  the  type  of 
pelvic  girdle  which  is  characteristic  of  the  family  and  that  in  all  essential  features  the 
pelvis  was  similar  to  those  of  the  living  otarids. 

Hind  Limb. 

Unfortunately,  all  of  the  hind  limb,  with  the  exception  of  the  femur  and  the  proxi¬ 
mal  ends  of  the  right  tibia  and  fibula,  was  destroyed  when  the  adjoining  slab  of  dia¬ 
tomaceous  earth  was  put  through  the  usual  processes  of  manufacture  at  the  Celite 
Products  Company  plant  at  Lompoc. 


Table  4. — Comparative  measurements  of  the  bones  of  the  hind  limb  (in  millimeters). 


Pithanotaria  starri, 
Lompoc,  California. 
Cat.  No.  11,  Mus. 
Stanford  University. 

r 

Callorhinus  alascanus, 
St.  Paul  Island,  Alas¬ 
ka.  2-year-old  c? . 
Cat.  No.  14222,  U.  S. 
Nat.  Mus. 

F  emur : 

Length  of  shaft,  capitulum  to  inner 
trochlea . 

X 

77 

Length  of  shaft,  greater  trochanter  to 
outer  trochlea . 

65 

70 

Least  depth  of  shaft . 

8.5 

11.3 

Greatest  depth  of  femur  at  distal  extrem¬ 
ity . 

22.2 

36.3 

Tibia: 

Length  of  shaft . 

X 

145 

Greatest  diameter  of  proximal  extremity 

32.5 

31.4 

Fibula : 

Length  of  shaft . . 

X 

122 

Greatest  diameter  of  proximal  extremity 

10 

12 

Femur. 

The  internal  half  of  the  shaft  of  the  right  femur  is  represented  in  the  impression 
shown  on  plate  12.  Except  for  its  slightly  smaller  size  and  the  more  oblique  truncation 
of  the  greater  trochanter,  this  femur  is  very  similar  to  the  corresponding  bone  in  a 
two-year-old  Callorhinus  alascanus  skeleton.  The  principal  features  of  this  bone  are 
not  indicated  by  the  outline  drawing  herewith  given  (fig.  1),  as  the  major  portion  of 
the  shaft  lies  below  the  surface  of  the  matrix.  The  epiphysis  of  the  greater  trochanter 


84  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


and  the  capitulum  appear  to  have  separated  from  the  shaft  before  this  impression  was 
formed.  Two  concavities  which  are  situated  between  the  end  of  the  shaft  and  the  ilium 
may  have  originated  from  these  epiphyses.  The  outer  condyle  of  this  femur  was  nearly 
flat  in  contrast  to  the  more  or  less  conical  condyle  of  a  two-year-old  Callorhinus  femur. 
The  curvature  of  the  shaft  is  practically  the  same  as  in  a  young  fur  seal.  The  patella 
is  flat  and  relatively  thin. 

Tibia  and  Fibula. 

The  proximal  ends  of  the  left  tibia  and  fibula  are  represented  by  impressions  of 
their  internal  surfaces.  The  relative  proportions  of  the  tibia  and  fibula  of  this  pinni¬ 
ped  correspond  to  the  fur  seal,  but  the  anterior  face  of  the  proximal  extremity  of  the 
tibia  appears  to  have  been  somewhat  flatter. 

Individual  II. 

Referred  specimen. — Cat.  No.  26784,  Museum  of  Palaeontology,  University  of 
California.  The  specimen  consists  of  a  slab  of  diatomaceous  earth  with  an  impression 
of  the  left  fore  limb.  The  scapula,  humerus,  radius,  and  ulna,  carpals,  metacarpals, 
and  the  proximal  ends  of  the  first  phalanges  are  represented. 

Occurrence. — The  Celite  Company’s  No.  15  quarry,  300  feet  west  from  the  north¬ 
west  corner  of  the  NE.  34  of  Section  22,  Township  6  North,  Range  34  West,  San 
Bernardino  Base  and  Meridian,  2.5  miles  south  and  east  of  Lompoc,  Santa  Barbara 
County,  California. 

Horizon. — This  specimen  was  found  by  laborers  in  the  quarry  of  the  Celite  Products 
Company  and  was  afterwards  presented  to  the  Museum  of  Palaeontology  by  Messrs. 
Edward  B.  Starr  and  Edward  J.  Porteous.  The  exact  level  at  which  this  specimen 
was  obtained  is  not  known  to  the  writer,  but  the  bed  is  approximately  1,400  feet  thick 
and  quarrying  operations  were  being  carried  on  at  several  levels  at  the  time  of  the 
writer’s  visit  in  1920.  Arnold  and  Anderson  stated  that  this  deposit  formed  part  of 
the  upper  division  of  the  Monterey  formation.  Sarmatian  or  Upper  Miocene. 

Fore  Limb. 

The  illustration  herewith  given  (fig.  2)  represents  a  cast  taken  from  the  original 
impression  in  the  slab  of  diatomaceous  earth.  Both  specimens  have  been  studied  and 
in  the  following  description  an  attempt  has  been  made  to  point  out  the  essential 
features  of  this  fore  limb  and  to  describe  peculiarities  which  were  not  shown  on  the 
type  specimen. 

Scapula. 

The  imprint  of  the  left  scapula  (fig.  2)  of  the  fossil  pinniped  from  Lompoc  shows 
that  the  general  conformation  of  this  bone  is  of  the  otarid  type,  although  the  neck  is 
relatively  shorter  and  the  blade  wider  but  not  as  deep  as  in  Callorhinus  and  Arcto- 
cephalus.  The  prescapular  fossa  is  very  large  and  the  ridge  which  projects  into  this 
fossa  is  slightly  curved.  In  front  of  this  ridge  the  coracoid  border  is  depressed  below 
the  level  of  major  portion  of  the  fossa.  Above  the  well-marked  coracoscapular  notch, 
the  coracoid  or  anterior  border  of  the  scapula  is  first  directed  obliquely  upward  and 
forward,  then  nearly  vertically,  and  obliquely  backward  superiorly.  The  suprascapular 
border  is  not  complete.  The  postscapular  fossa  is  relatively  narrow.  The  lower  por¬ 
tion  of  the  spine  with  its  acromion  process  was  broken  off  and  displaced  at  the  time 
this  impression  was  left  in  the  diatomaceous  earth.  The  lower  portion  of  this  spine 
is  shown  on  figure  2  behind  the  glenoid  border  of  the  scapula.  The  glenoid  fossa 
was  rather  large  and  appears  to  have  been  shallowly  concave. 

Humerus. 

The  left  humerus  of  this  otarid  differs  in  some  minor  details  from  those  of  the 
living  Callorhinus  alascanus  and  Arctocephalus  australis.  The  condition  of  the  lesser 
tuberosity  is  the  most  striking  peculiarity  of  this  humerus.  In  the  living  Callorhinus 


New  Pinnipeds  from  Vicinity  of  Lompoc ,  California.  85 


alascanus  and  Arctocephalus  australis  the  greater  tuberosity  is  twisted  backward  to  the 
right  side,  while  the  lesser  tuberosity  is  inclined  obliquely  forward;  the  two  tuberosities, 
although  closely  approximated,  are  separated  by  a  deep  sinus.  On  this  fossil  humerus 
the  greater  tuberosity  is  likewise  twisted  toward  the  right,  but  the  lesser  tuberosity  is 
erect  and  is  directed  almost  at  a  right  angle  to  the  sagittal  plane  of  the  deltoid  crest. 


Fig.  2. — Lateral  view  of  the  left  fore  limb  of 
Pithanotaria  starri,  internal  aspect.  Cat. 

No.  26784,  Mus.  Palaeont.,  Univ.  Calif. 

XH-  From  deposits  of  diatomaceous 
earth  near  Lompoc,  California.  The  same 
abbreviations  are  used  on  figs  2-3.  Ac, 
acromion  process  of  scapula ;  Cap.  capitulum 
of  humerus;  D,  deltoid  crest;  Gt.,  greater 
tuberosity;  Lt,  lesser  tuberosity;  M,  mag¬ 
num;  O.  pr.  olecranon  process;  Pi,  pisiform;  R,  radius;  Sc,  scapula;  Sc-Lu-Ce,  scapho-lunar- 
centrale;  Sp.  spine  of  scapula;  St.  styloid  process  of  ulna;  Tr,  inner  trochlea;  Trd,  trapezoid; 
Trm,  trapezium;  Tu,  tubercle  of  radius;  U,  ulna;  Ul,  ulnare;  TJn,  unciform;  I  to  V,  first  to 
fifth  metacarpals. 

Fig.  3. — Lateral  view  of  right  fore  limb  of  Eumetopias  jubata  (Schreber),  external  aspect.  Cat. 
No.  8821,  cf,  Mus.  Vert.  Zool.,  Univ.  Calif.,  X  Ano  Nuevo  Island,  off  San  Mateo 
County,  California. 


Trd. 


When  viewed  from  the  internal  side  (fig.  2)  the  anterior  border  of  the  humerus  is 
seen  to  curve  strongly  upward,  though  the  antero-posterior  diameter  of  the  shaft  in 
the  deltoid  region  is  not  conspicuously  greater  than  the  lower  trochlear  portion.  The 
deltoid  crest  is  well  developed  and  is  continued  downward  as  a  very  prominent  ridge  for 
about  five-sixths  of  the  length  of  the  shaft  and  then  merges  into  the  coronoid  fossa. 
This  crest  is  characterized  by  a  flaring  inner  margin  and  a  more  or  less  flattened  ante- 


86  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


rior  face.  The  lesser  tuberosity  is  thick  and  strongly  rugose,  and  terminates  below  the 
level  of  the  articular  face  of  the  head  as  in  the  living  fur  seals.  The  greater  tuberosity 
projects  slightly  above  the  level  of  the  head.  The  impression  of  the  inner  condyle  has 
been  destroyed,  but  the  crest  of  the  inner  trochlea  corresponds  to  that  of  Callorhinus 
alascanus . 

Radius. 

In  its  general  form  the  radius  of  this  pinniped  agrees  with  that  of  Callorhinus  and 
Ar otocephalus.  The  proximal  end  of  the  radius  is  broadly  oval  in  outline,  with  a  large 
concave  facet  for  the  reception  of  the  capitulum  of  the  humerus.  The  articular  surface 
of  the  tubercle  is  continuous  with  the  ulnar  facet.  This  peculiarity  distinguishes  this 
radius  from  those  of  Callorhinus  and  Ar otocephalus.  In  the  last-mentioned  genera 
there  is  a  distinct  interval  between  the  tubercle  and  the  ulnar  facet.  The  shaft  is  con¬ 
stricted  in  the  region  of  the  tubercle  and  in  cross-section  would  appear  nearly  circular. 
Below  this  neck-like  portion  the  shaft  is  compressed  from  side  to  side  and  greatly  ex¬ 
panded  in  an  antero-posterior  direction,  attaining  its  maximum  width  near  the  distal 
epiphysis.  The  curvature  of  the  shaft  agrees  with  that  of  Arctocephalus  australis,  but 
it  should  be  noted  also  that  the  anterior  margin  of  the  radius  is  missing.  There  is  a 
longitudinal  mesial  depression  on  the  internal  surface  of  the  distal  half  of  the  shaft. 
The  facets  on  the  distal  epiphysis  for  articulation  with  the  fused  scapho-lunar-centrale 
appear  to  correspond  in  all  essential  details  with  those  of  the  living  fur  seals. 

Ulna. 

The  outlines  of  the  ulna  are  not  as  clearly  shown  on  this  impression  as  might  be 
desired.  Of  the  olecranon  process  only  the  anterior  margin  is  visible  and  the  greater 
sigmoid  cavity  is  overlain  by  the  proximal  end  of  the  radius.  The  distal  extremity  of 
the  ulna  is  wedged  in  between  the  ulnare  and  pisiform.  The  anterior  face  of  the  ole¬ 
cranon  process  is  broad  and  rather  deeply  excavated.  Unless  the  olecranon  process 
has  been  distorted  by  pressure,  the  anterior  face  slopes  much  more  noticeably  toward 
the  inner  border  than  in  Arctocephalus.  The  inner  face  of  the  distal  end  of  the  shaft 
of  the  ulna  is  flattened  and  not  rounded  as  in  the  fur  seal. 

Carpus. 

Though  the  outlines  and  peculiarities  of  the  carpal  bones  are  difficult  to  interpret 
from  the  impressions  left  by  their  palmar  faces,  the  carpus  seems  identical  with  that 
of  the  otarids  in  proportions  and  in  structure.  Certain  minor  differences  are  to  be  ex¬ 
pected  in  any  genus  of  this  family.  In  the  sea  lion,  Eumetopias  jubata  (fig.  3),  the  ul¬ 
nare  is  not  interposed  between  the  radius  and  the  ulna,  and  the  last-mentioned  ele¬ 
ments  articulate  directly  with  each  other.  In  the  fur  seal,  Callorhinus  alascanus,  the 
ulnare  is  interposed  between  the  epiphysis  of  the  radius  and  the  styloid  process  of  the 
ulna,  and  each  of  these  elements  has  a  facet  for  articulation  with  the  ulnare.  The 
position  of  the  ulnare  appears  to  agree  more  closely  with  the  conditions  found  in  the 
Callorhinus  carpus  than  with  that  of  Eumetopias.  The  pisiform  is  relatively  slender. 
The  unciform  has  been  shifted  from  its  original  position  and  the  ulnar  surface  appar¬ 
ently  is  exposed  to  view.  In  comparison  to  Callorhinus  and  Eumetopias,  the  con¬ 
solidated  scapho-lunar-centrale  appears  rather  narrow,  with  well-developed  tuberosities 
near  the  inner  and  outer  angles.  The  magnum  and  trapezoid  are  rather  small  ele¬ 
ments  in  this  carpus.  The  trapezium  is  missing  from  this  carpus  if  the  other  elements 
have  been  correctly  interpreted.  All  the  elements  in  this  carpus  are  either  out  of  their 
normal  position  or  tilted  one  way  or  another. 

Metacarp  als. 

Viewed  from  the  palmar  side,  the  metacarpals  resemble  those  of  Callorhinus  alas¬ 
canus.  The  first  metacarpal  differs  from  the  others  in  its  greater  length  and  in  the 
expansion  of  the  proximal  end.  The  shaft  of  the  second  metacarpal  is  distinctly 
narrowud;  the  facets  for  the  third  metacarpal  and  trapezium  converge  on  the  palmar 


New  Pinnipeds  from  Vicinity  of  Lompoc,  California.  87 


face  and  are  separated  by  a  narrow  crest.  The  third  metacarpal  is  slightly  shorter 
than  the  second.  The  palmar  faces  of  the  proximal  ends  of  the  third  and  fourth 
metacarpals  are  broader  than  the  second.  As  in  the  living  otarids,  the  fifth  metacar¬ 
pal  is  more  robust  than  the  others  and  the  shaft  is  somewhat  wider  than  the  fourth. 


Table  5. — Comparative  measurements  of  the  fore  limbs  (in  millimeters ). 


Pithanotaria 
starri,  Lompoc, 
California. 
Cat.  No. 
26784,  Univ. 
California. 

Arctocephalus 
australis  St. 
Peter  &  Paul 
Ids.,  Strait  of 
Magellan.  Cat. 
No.  23331,  U. 
S.N.M. 

Callorhinus 
alascanus  St. 
Paul  Id.,  Alas¬ 
ka.  4  year  old. 
Cat.  No. 

14225, 

U.S.N.M. 

Scapula: 

Anterior  angle  to  inferior  angle . 

187  + 

216 

175 

Vertebral  margin  to  glenoid  concavity. 

130  + 

186.5 

148 

Anterior  margin  of  neck  to  inferior 
angle . 

155  ± 

186 

147.5 

Breadth  of  neck . 

33 

39 

31 

Humerus: 

Head  to  capitulum . 

123  + 

160 

132.2 

Greater  tuberosity  to  crest  of  inner 
trochlea . 

114 

174 

144.5 

Breadth  of  humerus  (lesser  tuberosity 
to  head) . 

X 

58.8 

51 

Breadth  of  humerus  (inner  condyle  to 
external  condyle) . 

X 

58 

55.5 

Greatest  depth  of  humerus  at  deltoid 
crest . . . 

38 

52 

39 

Least  breadth  of  humerus  near  middle 

X 

26 

22.1 

Radius : 

Greatest  length  of  radius . 

106 

175 

145 

Greatest  breadth  of  radius  at  proxi¬ 
mal  end . 

27.5 

r 

27.8 

24.8 

Greatest  breadth  of  radius  at  distal 
end . 

X 

55 

47.5 

Breadth  of  radius  across  tubercle . 

17.2 

18.5 

16 

Ulna: 

Greatest  length  of  ulna . 

139 

220 

172.2 

Inferior  margin  of  sigmoid  cavity  to 
superior  margin  of  olecranon  process. 

55 

85 

60 

Breadth  of  olecranon  process  at  in¬ 
ferior  margin  of  greater  sigmoid 
cavity . 

X 

38 

36 

Greatest  breadth  of  ulna  at  level  of 
base  of  the  distal  epiphysis . 

25 

22.5 

22 

Individual  III. 

Referred  specimen. — Cat.  No.  26785.  Museum  of  Palaeontology,  University  of  Cali¬ 
fornia.  Consists  of  impressions  of  the  right  and  left  hind  limbs  in  a  slab  of  diatom- 
aceous  earth.  All  the  elements  in  the  digits  of  both  limbs  are  represented,  including 
the  dorsal  faces  of  the  digits  in  the  right  limb  and  the  plantar  faces  of  the  digits  in  the 
left  limb.  Of  the  tarsal  bones  in  the  right  limb,  the  dorsal  faces  of  the  cuboid,  ecto- 
cuneiform,  and  (?)  mesocuneiform,  as  well  as  the  proximal  face  of  the  navicular,  are 
preserved;  the  other  tarsal  bones  either  are  missing  or  their  impressions  have  been 
defaced.  In  the  left  limb  the  plantar  view  of  the  cuboid,  the  fibular  view  of  the 
ectocuneiform,  the  tibial  view  of  the  calcaneum,  the  distal  view  of  the  navicular,  and 
the  head  of  the  astragalus  are  shown.  Median  sections  of  the  shafts  of  the  right 
tibia  and  fibula,  and  a  nearly  complete  left  tibia  with  an  unankylosed  distal  epiphysis 
are  also  present. 


88  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


Occurrence. — The  Celite  Company’s  No.  15  quarry,  300  feet  west  from  the  north¬ 
west  corner  of  the  NE.  34  of  Section  22,  Township  6  North,  Range  34  West,  San 
Bernardino  Base  and  Meridian,  2.5  miles  south  and  east  of  Lompoc,  Santa  Barbara 
County,  California. 


Fig.  4. — Views  of  a  cast  of  right  and  left 
hind  limbs  of  Pithanotaria  starri  taken 
from  the  original  slab  of  diatomaceous 
earth  obtained  near  Lompoc,  California. 
Cat.  No.  26785,  Mus.  Palaeont.,  Univ. 
Calif.  X3^.  The  same  abbreviations 
are  used  on  figs.  4  and  5. 

As.,  head  and  lower  portion  of  sustentacular 
facet  of  the  left  astragalus,  Ep.,  distal 
epiphysis  of  left  tibia;  L.C.,  plantar 
view  of  left  cuboid;  L.  Ca.,  tibial  view  of 
left  calcaneum;  L.  Ec.,  planto-fibular 
view  of  left  ectocuneiform;  L.  N.,  distal 
view  of  left  navicular;  L.T.,  left  tibia; 
R.C.,  dorsal  view  of  right  cuboid;  R.Ec., 
dorsal  view  of  right  ectocuneiform; 
R.F.,  right  fibula;  R.M.,  dorsal  view  of  right  (?)  mesocuneiform ;  R.N.,  proximal  view  of  left 
navicular;  R.T.,  right  tibia;  I  to  V,  first  to  fifth  metatarsals. 

Fig.  5. — Views  of  right  and  left  hind  limbs  of  Pithanotaria  starri  with  the  phalanges  transposed 
to  their  normal  positions.  From  deposits  of  diatomaceous  earth  near  Lompoc,  California. 

x  M. 


New  Pinnipeds  from  Vicinity  of  Lompoc ,  California.  89 


Horizon. — These  specimens  were  also  acquired  by  the  Museum  of  Palaeontology 
from  Messrs.  Edward  B.  Starr  and  Edward  J.  Porteous  of  the  Celite  Products  Company 
at  Lompoc,  California.  Sarmatian  or  Upper  Miocene. 

The  pinniped  to  which  these  hind  limbs  belonged  was  a  slightly  larger  individual 
than  the  type  and  may  have  been  either  a  slightly  older  individual  or  a  male. 

Tibia  and  Fibula. 

A  fairly  accurate  description  of  the  lower  limb  bones  (fig.  4)  can  be  given  as  median 
sections  of  the  shafts  of  the  right  tibia  and  fibula,  and  the  major  portion  of  the  shaft 
of  the  left  tibia  with  a  displaced  distal  epiphysis  are  represented  in  the  impressions. 
On  the  cast  the  internal  angle  of  the  shaft  of  the  left  tibia  faces  the  observer.  In 

curvature  and  proportions  it  resembles  that  of  Caliorhinus 
alascanus  very  closely.  The  distal  end  of  the  shaft  of  this 
tibia  is  roughly  three-sided,  the  anterior  and  internal  faces 
being  rounded  and  continuous,  while  the  posterior  and 
external  are  flattened  and  meet  at  an  angle.  The  shaft 
of  the  left  tibia  measures  125  mm.  in  length;  the  width 
of  the  distal  epiphysis  is  26  mm.  and  the  depth  19+ 
mm.;  the  length  of  this  epiphysis  is  approximately  15.5 
mm.  A  pair  of  vertical  grooves  traverses  the  internal 
face  of  the  epiphysis.  The  right  fibula  is  as  slender  as 
that  of  Caliorhinus. 

Calcaneum. 

Unfortunately,  the  left  calcaneum  (fig.  6)  alone  is 
represented  among  these  tarsal  impressions  and  a  con¬ 
siderable  portion  of  it  is  hidden  from  view  by  overlying 
bones.  Above  the  greater  process,  the  plantar  border  of 
the  left  calcaneum  is  overlain  by  the  distal  end  of  the 
shaft  of  the  left  tibia;  the  peroneal  tubercle  is  hidden  by 
the  close  approximation  of  the  left  cuboid  and  the  first 
metatarsal  of  the  right  limb;  the  proximal  end  is  overlain 
by  the  left  navicular;  and  the  major  portion  of  the  facet 
on  which  the  ectal  surface  of  the  astragalus  articulates  is 
not  represented  in  the  impression.  This  calcaneum  differs 
from  those  of  Ardocephalus  australis  and  Caliorhinus  alas¬ 
canus  in  several  respects.  The  most  obvious  peculiarity  of  this  tarsal  element  in  com¬ 
parison  to  those  of  the  above-mentioned  genera  is  the  obliquity  of  the  facet  for  the  cuboid 
and  the  less  noticeable  development  on  the  distal  extremity  of  the  tibio-dorsal  angle 
or  lesser  process.  The  facet  for  the  cuboid  is  ovoidal  in  outline  and  apparently  does 
not  occupy  more  than  one-half  of  the  distal  face  of  the  calcaneum.  The  above-men¬ 
tioned  lesser  process  is  merely  a  low  rounded  crest  and  the  surface  which  articulates 
with  the  sustentacular  facet  of  the  astragalus  is  continuous  with  the  facet  for  the 
cuboid  as  in  Caliorhinus.  Only  the  inferior  end  of  the  articular  surface  for  the  reception 
of  the  ectal  facet  of  the  astragalus  is  shown  in  this  impression.  This  facet  does  not 
extend  across  the  tibial  face  of  the  dorsal  border  as  in  all  of  the  living  otarids  and 
barely  crosses  the  median  sagittal  plane  of  the  shaft  of  the  calcaneum.  In  this  feature 
it  resembles  the  calcaneum  of  Pontolis  cf.  magnus  (see  p.  102).  The  groove  for  the 
interosseous  ligament  appears  to  be  shallow,  as  In  Caliorhinus. 

Astragalus. 

Neither  the  plantar  nor  the  dorsal  surfaces  of  the  astragalus  is  included  among  the 
impressions  of  the  tarsals.  No  trace  of  a  right  astragalus  can  be  found  and  only  a 
portion  of  the  head  of  the  left  is  represented.  The  internal  angle  of  the  head  of  this 
astragalus  is  relatively  thicker  than  in  either  Ardocephalus  or  Caliorhinus.  The 


\ 

\ 


Fig.  6. — Tibial  view  of  left 
calcaneum  of  Pithano- 
taria  starri.  Cat.  No. 
26785,  Mus.  Pal- 
aeont.,  Univ.  Calif. 
Xl+f.  Diatomaceous 
earth  near  Lompoc, 
California. 


90  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


distal  surface  of  the  head  is  convex  in  all  directions  and  serves  as  the  articular  surface 
for  the  proximal  facet  of  the  navicular;  in  outline  it  is  almost  kidney-shaped.  Turning 
to  the  plantar  surface  of  the  head,  other  differences  may  be  pointed  out.  There  is  a 
rather  deep  groove  invading  the  sustentacular  facet  from  the  internal  border  and 
ending  about  two-thirds  of  the  distance  across  the  head  on  those  of  living  otarids.  A 
similar  groove  is  present  on  this  fossil  astragalus,  but  it  is  very  shallow.  The  susten¬ 
tacular  facet  also  approaches  nearer  to  the  internal  border  of  the  neck  than  in  living 
otarids. 

Navicular. 

Both  naviculars  are  represented  in  the  impressions  of  the  tarsal  bones.  This  tarsal 
element  is  extraordinarily  broad  and  subquadrangular  in  outline.  Its  proportions  are 
quite  different  from  those  of  Callorhinus,  Zalophus,  and  Eumetopias,  and  as  a  whole 
bear  a  much  closer  resemblance  to  those  of  Ar otocephalus.  The  proximal  facet  of  the 
right  navicular  (fig.  7)  for  articulation  with  the  head  of  the  astragalus  is  deeply 
concave,  with  a  sudden  upward  curvature  toward  the  tibial  and  fibular  borders.  The 
curvature  of  the  dorsal  margin  of  this  facet  is  regular  in  contrast  to  the  medial  de¬ 
pression  on  those  of  Callorhinus ,  Ar otocephalus,  and  Zalophus.  The  fibular  border  is 
much  shorter  than  the  tibial;  the  facet  for  the  cuboid  is  short  and  obliquely  truncated. 
In  outline  the  distal  face  of  the  left  navicular  (fig.  7)  bears  some  resemblance  to  that 
of  Arctocephalus.  The  tuberosity  on  the  plantar  face  of  the  navicular,  which  in  living 
otarids  is  directed  toward  the  fibular  border,  is  placed  nearest  to  the  tibial  or  postero¬ 
internal  angle.  There  are  three  facets,  though  continuous  with  one  another,  on  the 
distal  face  of  the  navicular  of  Arctocephalus;  the  largest  facet  articulates  with  the 
entocuneiform  and  extends  about  halfway  across  this  face;  the  other  two  facets 
articulate  with  the  meso-  and  ectocuneiform.  The  most  distal  portion  of  the  navicular 
is  at  the  crest  which  separates  the  facets  for  the  ento-  and  mesocuneiforms.  On  this 
fossil  navicular  the  facets  for  the  three  cuneiforms  are  not  as  distinct;  the  internal  half 
of  this  face  is  nearly  flat  and  horizontal,  while  the  external  curves  upward  toward  the 
fibular  and  plantar  borders.  In  comparison  with  that  of  Arctocephalus,  the  facet  for 
the  entocuneiform  is  not  as  wide  as  it  extends  less  than  halfway  across  the  tibial 
border.  In  this  respect,  it  agrees  more  closely  with  that  of  Callorhinus  than  with 
Arctocephalus.  The  depressed  rugose  area,  which  in  living  otarids  restricts  the  facets 
for  the  cuneiforms  from  the  plantar  half  of  this  face,  is  not  developed  on  this  fossil 
navicular.  The  tubercle  at  the  tibial  or  postero-internal  angle  is  more  prominent  than 
in  Arctocephalus.  The  dorso-fibular  angle  is  rounded  off,  but  the  dorso-tibial  angle  is 
nearly  square. 


Table  6. — Comparative  measurements  of  the  navicular  (in  millimeters) . 


Pithanotaria  starri, 
No.  26785,  U.  C. 

Arctocephalus 
australis,  No.  23331, 
U.S.N.M. 

Callorhinus  alas- 
canus,  No.  20866, 
U.S.N.M. 

Tibio-fibular  diameter . 

23.5  + 

26.1 

28 

Greatest  dorso-plantar  di- 

ameter . 

18.8 

23 

26.3 

Cuboid. 

This  cuboid  is  slightly  smaller  than  that  of  Arctocephalus  australis,  but  the  astragalo- 
cuboid  contact  is  essentially  the  same.  The  dorsal  surface  of  the  right  cuboid  (fig.  8) 
and  the  curvature  of  the  proximal  facet  for  the  calcaneum  are  very  clearly  shown  on 
this  cast.  From  a  dorsal  view,  this  cuboid  resembles  that  of  Arctocephalus  more 
closely  than  that  of  Callorhinus.  The  upward  slope  of  the  calcanear  facet  is  not  nearly 
as  oblique  as  in  Callorhinus  and  corresponds  more  closely  with  that  of  Arctocephalus, 


New  Pinnipeds  from  Vicinity  of  Lompoc ,  California.  91 


but  the  anterior  border  is  rounded  off  and  not  crest-like  as  in  the  latter.  On  the  tibial 
border  and  about  6  mm.  below  the  summit  of  the  calcanear  facet,  there  is  a  small 
projecting  ovoidal  facet  for  articulation  with  the  antero-external  angle  of  the  navicular. 
Similar  facets  are  present  on  the  cuboids  of  Ardocephalus  and  Callorhinus ,  but  they 
do  not  project  beyond  the  level  of  the  tibial  border.  The  proximal  and  distal  portions 
of  this  cuboid  are  nearly  equal  in  diameter  in  contrast  to  the  proximal  expansion  of  the 
Ardocephalus  cuboid.  The  curvature  of  the  distal  border  of  the  anterior  face  agrees 
with  that  of  Callorhinus.  Some  well-marked  peculiarities  characterize  the  plantar  face 
of  the  left  cuboid  (fig.  8).  The  groove  for  the  peroneus  longus  is  sharply  defined 
and  curves  upward  from  the  tibial  border.  The  tuberosity  is  small  and  rounded  and 
does  not  extend  entirely  across  the  plantar  face  as  in  Ardocephalus.  On  the  cuboid 
of  Callorhinus  the  groove  for  the  peroneus  longus  is  shallow  and  the  course  of  the 
groove  is  nearly  horizontal;  the  tuberosity  is  low,  rounded,  and  poorly  defined.  On 


B 


B 


Fig.  7. — Navicular  of  Pithanotaria  starri. 
Cat.  No.  26785,  Mus.  Palaeont., 
Univ.  Calif.  Diatomaceous  earth 
near  Lompoc,  California.  A,  proxi¬ 
mal  view  of  right  navicular ;  B,  distal 
view  of  left  navicular.  Xlh£. 


Fig.  8. — Cuboid  of  Pithanotaria  starri. 
No.  26785,  Mus.  Palaeont.,  Univ. 
Calif.  Diatomaceous  earth  near  Lom¬ 
poc,  California.  A,  dorsal  view  of 
right  cuboid;  B,  plantar  view  of  left 
cuboid.  Xl}£. 


the  cuboids  of  Ardocephalus  and  Callorhinus  there  is  a  deep  excavation  behind  the 
calcanear  facet  and  above  the  tuberosity.  This  excavation  is  not  present  on  the  left 
cuboid  of  this  fossil  pinniped,  and  this  portion  of  the  tarsal  agrees  more  closely  with 
that  of  Monachus  tropicalis,  although  the  cuboid  of  the  latter  otherwise  is  quite  differ¬ 
ent.  The  distal  border  of  the  plantar  face  of  this  fossil  cuboid  is  shallowly  concave. 


Table  7. — Comparative  measurements  of  the  cuboid  (in  millimeters). 


Pithanotaria  starri, 
No.  26785,  U.  C. 

Arctocephalus 
australis,  No.  23331, 
U.S.N.M. 

Callorhinus  alas- 
canus,  No.  29866, 
U.S.N.M. 

Breadth  of  anterior  face  of 
cuboid  at  level  of  lower 
margin  of  proximo-tibial 
facet  for  the  navicular . 

12.2 

17.2 

16 

Breadth  of  anterior  face  of 
cuboid  at  distal  extremity. 

13.6 

15.3 

16.2 

Length  of  cuboid  from  sum¬ 
mit  of  calcanear  facet  to 
tibio-distal  angle . 

24.5 

24.6 

30.8 

Breadth  of  plantar  facet  of 
cuboid  at  distal  extremity 

15 

17.5 

26.3 

Entocuneiform. 

An  imperfect  impression  of  what  appears  to  be  the  right  entocuneiform  lies  im¬ 
mediately  above  the  head  of  the  first  right  metatarsal.  One  can  not  be  certain  of 
the  surface  which  is  exposed,  as  a  portion  of  this  tarsal  has  been  destroyed. 


92  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


Mesocuneiform. 

If  the  impression  which  is  assumed  to  be  the  right  mesocuneiform  has  been  correctly 
identified,  then  it  was  relatively  smaller  than  the  same  element  in  the  tarsus  of  Cal- 
lorhinus  and  of  approximately  the  same  proportions  as  that  of  Ar otocephalus.  It  is 
wedged  in  between  the  right  ectocuneiform  and  the  head  of  the  second  metatarsal. 

Ectocuneiform. 

In  general  appearance,  the  left  ectocuneiform  differs  from  those  of  Ardocephalus 
and  Callorhinus  in  many  respects.  The  plantar  face  is  nearly  flat  and  obliquely 
truncated.  The  blunt  process  which  is  developed  on  the  proximal  half  of  the  plantar 
face  of  the  ectocuneiform  of  living  otarids  is  absent.  The  proximal  facet  for  the 
navicular  is  slightly  convex.  An  obliquely  placed  depression  is  present  on  the  fibular 
face.  Very  little  additional  information  can  be  given  for  the  right  ectocuneiform;  the 
anterior  face  of  this  tarsal  is  shown  on  figure  4. 

Digits. 

In  the  relative  lengths  of  the  metatarsals  and  phalanges,  the  digits  (figs.  4  and  5) 
of  this  pinniped  are  slightly  smaller  than  those  of  a  two-year-old  Callorhinus  alascanus. 
These  flippers  also  agree  with  those  of  living  otarids  in  that  the  first  and  fifth  digits 
did  not  bear  nails  and  their  ungual  phalanges  are  flattened  in  a  dorso-plantar  direction, 
constricted  mesially,  and  expanded  from  side  to  side  distally.  The  ungual  phalanges 
of  the  second,  third,  and  fourth  digits  are  modified  to  support  nails.  The  general 
resemblance  of  these  digits  to  those  of  a  living  fur  seal  is  remarkably  close. 

The  first  digit  consists  of  a  metatarsal  and  two  phalanges;  the  other  digits  have  a 
metatarsal  and  three  phalanges.  The  first  metatarsal  is  quite  similar  to  that  of 
Callorhinus.  It  is  longer  than  all  the  other  metatarsals.  The  internal  view  of  the  right 
and  the  plantar  view  of  the  left  first  metatarsal  are  shown  on  figure  4.  The  shaft 
of  this  metatarsal  is  relatively  thicker  nearer  the  proximal  end  than  in  Callorhinus 
and  the  distal  end  is  almost  circular.  There  is  a  shallow  longitudinal  depression  on 
the  proximal  half  of  the  plantar  face  of  the  left  metatarsal.  The  proximal  end  is 
occupied  by  a  large  facet  and  the  surface  slopes  upward  toward  the  fibular  margin. 
The  shaft  of  the  second  metatarsal  is  slender  and  nearly  straight.  On  the  tibial  surface 
and  along  the  proximal  border  there  is  a  narrow  facet  for  articulation  with  the  ento- 
cuneiform.  As  in  Callorhinus  there  is  no  articular  surface  for  the  head  of  the  first 
metatarsal.  The  plantar  face  of  the  shaft  of  the  left  metatarsal  is  rounded.  The 
head  of  the  third  metatarsal  is  larger  than  that  of  the  second.  The  articular  surface 
on  the  proximal  end  slopes  obliquely  from  the  tibial  to  the  fibular  border.  A  promi¬ 
nent  knob-like  process  or  tuberosity  is  developed  on  the  tibial  face  of  the  head.  The 
shaft  is  nearly  circular  in  cross-section  and  approximately  of  equal  width  throughout 
its  length.  The  head  of  the  fourth  right  metatarsal  is  concealed  by  the  close  approxi¬ 
mation  of  the  third  and  fifth  metatarsals.  A  narrow  crest  on  the  plantar  face  of  the 
head  of  the  left  fourth  metatarsal  marks  the  contact  of  the  facet  for  the  third  meta¬ 
tarsal  and  a  similar  facet  for  the  fifth.  The  shaft  is  slightly  longer  than  the  third,  but 
otherwise  it  is  very  similar.  In  general  features  the  fifth  metatarsal  does  not  differ 
from  those  of  Ardocephalus  and  Callorhinus.  A  concave  facet  for  the  head  of  the 
fourth  metatarsal  occupies  the  tibial  face  of  the  head.  The  external  angle  of  the  head 
is  prolonged  upward  and  on  the  plantar  face  attains  a  much  higher  level  than  the 
dorsal  margin  of  the  facet  for  the  cuboid.  The  shaft  is  abruptly  narrowed  below  the 
head,  but  the  distal  extremity  is  slightly  expanded. 

The  plantar  surfaces  of  the  shafts  of  the  first  phalanges  are  characterized  by  a  median 
longitudinal  depression  and  their  dorsal  surfaces  are  rounded.  The  first  phalanges  of 
the  first  and  fifth  digits  are  longer  and  stouter  than  the  others.  The  second  phalanges 
of  the  second  to  fifth  digits  inclusive  have  their  plantar  faces  flattened  and  their 
dorsal  faces  rounded;  the  shafts  taper  toward  the  distal  end. 


New  Pinnipeds  from  Vicinity  of  Lompoc ,  California.  93 


Table  8. — Comparative  measurements  of  the  greatest  length  of  metatarsals  and  phalanges 

(in  millimeters ) . 


Callorhinus  alascanus, 
St.  Paul  Island,  Alas¬ 
ka,  2-year-old  cf .  No 
14222,  U.S.N.M. 

Pithanotaria  starri, 
Lompoc,  California. 

No.  26785,  Mus. 
Paleont.,  University 
California. 

First  metatarsal . 

57 

65 

First  phalange  of  first  digit . 

54.5 

52  5 

Second  phalange  of  first  digit . . . 

20 

16 

Second  metatarsal . 

44 

53 

First  phalange  of  second  digit . 

44 

38  5 

Second  phalange  of  second  digit . 

37 

34 

Third  phalange  of  second  digit . 

20 

18  5 

Third  metatarsal . . . 

44 

48 

First  phalange  of  third  digit . 

43.5 

39 

Second  phalange  of  third  digit . 

44 

34 

Third  phalange  of  third  digit . 

17 

13 

Fourth  metatarsal . . 

46.5 

49 

First  phalange  of  fourth  digit . 

45 

38.5 

Second  phalange  of  fourth  digit . 

37 

36 

Third  phalange  of  fourth  digit . 

17 

15 

Fifth  metatarsal . 

51 

58.5 

First  phalange  of  fifth  digit . . . 

49 

45 

Second  phalange  of  fifth  digit . . . 

35 

38.2 

Third  phalange  of  fifth  digit . 

13 

13.5 

Otarid  (?),  new  genus  and  species. 

From  time  to  time  bones  of  pinnipeds  in  a  more  or  less  perfect 
state  of  preservation  are  found  in  marine  Tertiary  deposits  on  the 
Pacific  Coast  of  North  America.  Many  of  these  are  discarded  by  the 
collectors  soon  after  discovery  because  of  the  prevailing  impression 
that  it  is  futile  to  attempt  to  determine  such  fragmentary  material. 
Fortunately,  a  number  of  these  specimens  have  found  their  way  into 
collections  on  the  Pacific  Coast  and  in  the  course  of  a  rather  cursory 
examination  of  this  material  a  number  of  interesting  pinnipeds  have 
been  discovered.  Some  of  them,  in  so  far  as  can  be  determined  from 
the  meager  skeletal  evidence,  exhibit  resemblances  to  the  family 
Otariidse.  One  of  these  pinnipeds  was  obtained  from  the  same  forma¬ 
tion  as  Pithanotaria  starri,  and  although  the  material  is  too  incom¬ 
plete  to  warrant  the  application  of  a  scientific  name,  it  is  apparent 
that  it  represents  a  new  type. 

Specimens. — Cat.  No.  24221,  distal  end  of  the  right  tibia,  and  Cat.  No.  24222,  four 
closely  appressed  ribs  from  the  left  side  of  the  body,  Museum  of  Palaeontology,  Uni¬ 
versity  of  California. 

Occurrence. — On  northeast  side  of  the  first  canyon  entering  San  Miguelito  Creek 
Canyon  from  the  east  and  0.5  mile  northeast  of  855-foot  elevation  hill  (Lompoc 
Quadrangle,  U.  S.  Geol.  Surv.),  and  on  the  opposite  side  of  the  canyon  from  Quarry 
No.  9  of  the  Celite  Products  Company.  Southwest  hi  of  section  15,  township  6  N., 
range  34  W.  This  site  is  1.5  miles  south  and  east  of  Lompoc,  Santa  Barbara  County, 
California.  Locality  No.  3545,  Museum  of  Palaeontology. 


94  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast . 


Horizon. — The  bones  were  discovered  by  Mr.  Edward  J.  Porteous  during  the 
month  of  October  1920,  while  examining  the  exposure  of  diatomaceous  earth  on  the 
opposite  side  of  the  canyon  from  a  quarry  then  in  operation.  It  is  impossible  to  state, 
at  the  present  writing,  the  exact  level  in  the  beds  where  these  remains  were  found. 
Sarmatian  or  Upper  Miocene. 


Fig.  9. — Right  tibia  of  an  Otarid(?).  Cat. 
No.  24221,  Mus.  Palaeont.,  Univ.  Calif. 
Diatomaceous  earth  near  Lompoc, 
California.  A,  anterior  view;  B,  distal 
view.  X34- 

Fig.  10. — Left  rib  of  an  Otarid  (?).  Cat. 
24222,  Mus.  Palaeont.,  Univ.  Calif. 
Diatomaceous  earth  near  Lompoc, 
California.  A,  external  view;  B ,  internal 
view.  X3^. 


Tibia. 

The  lower  extremity  of  the  tibia  is  expanded  laterally,  principally  on  the  internal 
side.  The  distal  end  is  thicker  as  well  as  broader  than  the  portion  of  the  shaft  just 
above  it.  The  internal  surface  is  continued  down  beyond  the  rest  of  the  lower  extremity 
to  form  the  internal  malleolus  and  narrows  perceptibly  towards  the  point.  The 
external  or  fibular  surface  of  the  shaft  is  much  broader  than  the  internal  and  on  the 
lower  margin  there  is  an  elongated  concave  facet  for  articulation  with  the  fibula. 
The  lower  margin  of  the  posterior  surface  of  the  distal  end  is  strongly  convex  from  side 
to  side  in  contrast  to  the  flattened  appearance  of  the  same  portion  of  the  tibia  of 
Eumetopias  jubata. 

From  a  distal  view  (fig.  9)  the  internal  malleolus  is  observed  to  terminate  in  a 
pointed  protuberance  and  is  separated  from  the  astragalar  facet  by  a  roughened 
surface.  The  main  articular  facet  for  the  astragalus  consists  of  two  surfaces,  separated 
from  each  other  by  a  slightly  curved  ridge,  the  inner  one  being  nearly  twice  as  large 
as  the  outer,  and  concave  in  both  directions;  the  outer  surface  is  concave  from  before 
backwards  and  is  continuous  externally  with  the  fibular  facet.  There  is  a  third  surface, 
however,  anterior  to  these  which  is  directed  obliquely  upward  and  articulated  with 
the  trochlea  of  the  astragalus. 

This  fragment  of  the  right  tibia  (fig.  9)  has  been  compared  with  all  of  the  living 
otarid  genera  and  with  Odobenus.  Of  these  pinnipeds,  the  tibia  of  Odobenus  exhibits 
the  closest  resemblance.  Somewhat  similar  modifications  are  present  on  the  tibia  of 
Ar otocephalus.  The  distal  articular  surface  is  divided  into  the  same  number  of  facets 
as  in  Odobenus  and  these  facets  correspond  with  one  another  not  only  in  extent  but  also 
in  position.  The  presence  of  a  long,  narrow  facet  along  the  anterior  border  suggests 


New  Pinnipeds  from  Vicinity  of  Lompoc ,  California.  95 


articulation  with  an  astragalus  of  the  Odobenus  type.  In  the  latter,  the  external 
prolongation  of  the  head  of  the  astragalus  is  much  less  developed  than  in  Arcto- 
cephalus;  the  facet  on  the  external  face  of  the  head  for  articulation  with  the  distal 
extremity  of  the  fibula  is  more  or  less  flattened,  while  the  same  surface  is  deeply 
concave  in  the  latter.  The  narrow  anterior  facet  on  the  distal  face  of  the  tibia  appears 
to  be  correlated  with  a  broad,  shallow  trochlea  on  the  astragalus. 

Ribs. 

Four  crushed  and  incomplete  ribs  from  the  left  side  of  the  body  were  found  associated 
with  the  fragment  of  the  right  tibia.  One  of  these  (figs.  10a,  106)  was  selected  for 
illustration.  The  shafts  of  all  of  these  ribs  are  relatively  heavy  as  compared  to  those 
of  Zalophus.  The  shaft  of  the  rib  figured  herewith  measures  20  mm.  in  width  and  21 
mm.  in  thickness  at  a  point  70  mm.  below  the  tuberculum.  The  external,  anterior, 
and  posterior  faces  of  the  shaft  are  more  or  less  flattened,  but  the  internal  face  is 
depressed,  with  the  posterior  margin  rounded  off  and  the  anterior  forming  a  rather 
sharp  crest.  The  tuberculum  is  relatively  small,  compressed  from  side  to  side,  and  its 
articular  surface  slopes  obliquely  upward.  The  neck  is  thin  and  rather  wide.  The 
capitulum  consists  of  two  articular  facets  which  are  continuous  anteriorly  although 
there  is  a  V-shaped  indentation  interiorly.  These  two  facets  are  convex  in  all  directions 
and  are  approximately  equal  in  size. 


V.  STRUCTURE  OE  THE  FLIPPER  OF  A  PLIOCENE  PINNIPED 
FROM  SAN  DIEGO  COUNTY,  CALIFORNIA. 

The  pinniped  remains,  from  the  Fernando  formation,  which  form 
the  subject  of  the  present  paper,  were  obtained  by  Oscar  Mitchell  in 
the  fall  of  1919  in  exposures  on  the  south  side  of  Soledad  Canyon,  San 
Diego  County,  California.  During  the  month  of  November  in  the 
same  year,  Dr.  Chester  Stock,  while  engaged  in  geological  work  in 
San  Diego  County,  was  informed  that  a  boy  had  discovered  a  sand¬ 
stone  nodule  containing  fossil  bones.  Dr.  Stock  obtained  permission 
to  examine  the  nodule,  and  found  that  it  contained  part  of  the 
right  hind-limb  of  some  pinniped.  Through  the  generosity  of  the 
boy’s  father,  Mr.  J.  W.  Mitchell,  the  Department  of  Palaeontology 
of  the  University  of  California  a  short  time  later  came  into  possession 
of  the  specimen. 

As  recently  as  1906,  the  number  of  fossil  Otariidae  known  from 
North  America  was  limited  to  two  more  or  less  doubtfully  allocated 
forms  from  the  coast  of  Oregon.  Important  information  relative  to 
the  exact  site  of  discovery,  including  the  proper  horizon,  either  was 
not  available  or  was  neglected  by  the  original  describers,  and  for 
this  reason  the  two  forms  have  for  some  time  offered  a  serious 
problem  in  age  determination. 

Following  the  discovery  of  Desmatophoca  oregonensis1 2  in  sandstone 
exposures  about  8  miles  south  of  Yaquina  Bay  on  the  coast  of 
Lincoln  County,  Oregon,  there  came  to  light  in  the  Coos  Bay  region 
another  pinniped  which  has  been  named  Pontolis  magnus ?  More 
recently  a  third  pinniped  of  large  size,  Pliopedia  pacifica ,3  was 
found  near  Santa  Margarita,  San  Luis  Obispo  County,  California, 
and  has  added  some  additional  information  regarding  the  fossil 
pinnipeds  of  the  Pacific  Coast. 

According  to  Wortman4  there  is  some  evidence  which  supports  the 
assumption  that  the  formation,  from  which  Desmatophoca  oregonensis 
came,  may  possibly  be  equivalent  in  time  to  the  middle  Oligocene  of 
our  interior  series.  More  recently,  Arnold  and  Hannibal5  have 
referred  beds  in  this  area  to  the  Oligocene-Miocene. 

Although  the  skull  of  Pontolis  magnus  was  found  in  a  formation 
assumed  to  be  part  of  the  “  Empire  beds,”  the  exact  location  is  quite 

1  T,  Condon,  Univ.  Oregon  Bull.,  Suppl.,  vol.  3,  No.  3,  pp.  5-14,  pla.  1-2,  with  3  text  figs., 
1905;  O.  P.  Hay,  Proc.  U.  S.  Nat.  Mus.,  vol.  49,  Publ.  2113,  p.  383,  1915. 

2  F.  W.  True,  Smithson.  Misc.  Coll.  (Quart.  Issue),  vol.  48,  pt.  1,  Publ.  1577,  p.  48,  1905; 
Prof.  Paper,  No.  59,  U.  S.  Geol.  Surv.,  pp.  144-147,  pis.  21-23,  1906. 

3  R.  Kellogg,  Journ.  Mammalogy,  vol.  2,  No.  4,  pp.  212-226,  with  13  text  figs.,  1921. 

4  J.  L.  Wortman,  Science,  n.  s.,  vol.  24,  No.  603,  pp.  89-92,  1906. 

6  R.  Arnold  and  H.  Hannibal,  Proc.  Amer.  Philos.  Soc.,  vol.  52,  No.  212,  pp.  582,  587,  pi.  38, 
1913;  H.  Hannibal,  Journ.  Mammalogy,  vol.  3,  No.  4,  p.  239,  1922. 

97 


98  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


indefinite,  for  True  states  that  the  skull  was  found  in  a  sandstone 
bluff  on  the  east  side  of  the  lower  part  of  Coos  Bay,  between  Empire 
City  and  the  “north  slough.”  While  the  exact  place  of  discovery  is 
not  definitely  known,  information  from  other  sources  indicates  that 
Pontolis  belongs  to  the  Pliocene  period.  Howe1  has  brought  forth 
evidence  to  show  that  the  Empire  formation  is  lower  Pliocene.  At 
present  the  skeleton  of  Pontolis  magnus  is  unknown,  while  we  have 
only  the  right  hind-flipper  of  the  skeleton  of  the  present  pinniped. 

Thus  the  occurrence  of  Pontolis  magnus  in  the  Pliocene  beds  of 
Oregon  furnishes  additional  evidence  that  this  fossil  flipper  from  the 
Fernando  formation  in  California  may  possibly  belong  to  the  same 
genus  and  even  to  the  same  species.  Judging  from  the  proportions 
of  the  skull,  which  the  writer  has  recently  examined,  Pontolis  magnus 
was  a  large  pinniped,  whose  proportions  were  unquestionably  similar 
to  the  animal  to  which  the  present  flipper  belonged. 

An  additional  metapodial  has  recently  been  placed  in  the  hands  of 
the  writer.  It  represents  the  first  metatarsal,  and  apparently  belongs 
to  the  same  species  as  the  flipper  from  the  Fernando  exposures  in 
Soledad  Canyon.  This  specimen  was  found  during  the  month  of 
March  in  1920  by  Mr.  Howell  Gester,  of  the  geological  staff  of  the 
Standard  Oil  Company,  in  a  bed  (Museum  of  Palaeontology,  locality 
No.  3584)  of  presumably  the  same  age  as  that  from  whence  the 
nodule  containing  the  flipper  came.  Accompanying  the  metapodial 
were  the  following  data: 

Occurrence:  Section  27,  township  4  north,  range  15  west,  near  the  section  line 
directly  west  of  2,006'  elevation  hill.  Bone  was  found  in  sandy  shale  formation  im¬ 
mediately  below  a  conglomerate  layer  about  6  feet  in  thickness.  In  the  same  layer 
in  which  metapodial  was  found,  the  following  shells  were  also  collected:  Terebratala 
n.  sp.,  Phacoides  sactaecrucis? ,  and  a  pecten  which  may  possibly  be  Pecten  estrellanis. 
Above  the  conglomerate  are  several  hundred  feet  of  sandy  shale  in  which  a  lower 
Fernando  invertebrate  fauna  was  found.  (On  U.  S.  Geol.  Surv.,  Fernando  Quadrangle, 
Los  Angeles  County,  California.) 

Pontolis  cf.  magnus  True. 

In  the  nodule  from  Soledad  Canyon  (Museum  of  Palaeontology,  locality  No.  3585). 
and  associated  with  the  fossil  flipper,  were  fragments  of  two  mollusks,  one  of  which 
was  determined  by  Dr.  Bruce  L.  Clark  as  Leda  taphra,  while  the  other  represents  some 
gasteropod.  The  occurrence  of  this  nodule  is  as  follows:  SW  quarter  of  NE  quarter 
of  section  27,  township  4  north,  range  15  west,  on  the  south  side  of  Soledad  Canyon 
and  near  the  town  of  Humphreys,  San  Diego  County,  California. 

This  flipper  is  quite  unusual  in  many  respects,  and  differs  in  some  important  features 
from  living  pinnipeds.  Though  at  first  glance  certain  features  resemble  the  Cysto- 
phorinae,  especially  the  genus  Mirounga,  these  characters  are  superficial  and,  appar¬ 
ently,  have  no  important  bearing  on  the  relationships  of  the  specimen  in  question. 
After  a  careful  comparison  with  many  living  pinnipeds,  the  writer  is  convinced  that 
this  specimen  possesses  a  number  of  unusual  characters,  which  are  quite  unlike  any 
other  known  pinniped,  though  its  relationships  are  with  the  sea-lions  and  the  walruses, 


1  H.  V.  Howe,  Univ.  Calif.  Publ.,  Bull.  Dept.  Geol.  Sci.,  vol.  14,  No.  3,  pp.  85-114,  1922. 


Structure  of  a  Flipper  of  a  Pliocene  Pinniped . 


99 


rather  than  with  the  true  seals.  A  considerable  number  of  pinnipeds  were  critically 
examined,  but  were  found  either  to  be  allied  to  this  fossil  specimen,  or  to  be  so  unlike 
as  not  to  be  pertinent  in  the  present  study.  The  following  among  those  examined 
were  found  to  show  certain  resemblances:  Odobenus  divergens,  Eumetopias  jubata, 
Arctocephalus  australis ,  Zalophus  calif ornianus,  and  Mirounga  angustirostris.  In  most 
respects  the  tarsal  elements  of  the  hind-limb  of  the  Phocidae  are  quite  unlike  this 
fossil  flipper,  while  the  Odobenidae  and  Otariidae,  which  morphologically  are  closely 
allied  to  one  another,  possess  many  features  in  common  with  this  Pliocene  pinniped. 


The  extension  of  the  fibular  facet  of  the  astragalus  distally  upon  the  neck  is  a  feature 
that  is  not  found  in  any  other  pinniped.  This  modification  is  accompanied  by  the  loss 
of  the  external  portion  of  the  body  of  that  bone.  The  astragalo-cuboid  contact  is 
smaller  than  in  our  living  otarids.  However,  this  fossil  flipper  resembles  the  sea-lions 
in  so  many  features,  even  though  some  are  considerably  modified,  that  it  is  referred 


100  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


tentatively  to  the  Otariidae.  Should  more  of  the  skeleton  become  known,  it  may 
eventually  be  allocated  to  its  proper  group.  It  is  hardly  possible  that  this  Pliocene 
pinniped  is  one  of  the  forebears  of  the  living  Otariidae,  but  more  probably  it  repre¬ 
sents  a  somewhat  highly  modified  offshoot  which  became  extinct  some  time  during  the 
Pliocene. 


Fig.  2. — Right  hind  flipper  of  Pontolis  cf.  magnus,  Nos.  24070-82,  Mus.  Palaeo.,  Univ.  Calif., 
X0.5.  Exposures  on  south  side  of  Soledad  Canyon,  San  Diego  County,  California; 
a,  superior  view;  b,  lateral  view. 


On  the  other  hand,  the  possession  by  this  fossil  pinniped  of  a  number  of  structural 
modifications  peculiar  to  the  Odobenidae  is  a  further  indication  that  fossil  walruses  may 


Structure  of  a  Flipper  of  a  Pliocene  Pinniped. 


101 


be  expected  in  Miocene  beds  on  the  Pacific  coast,  and  affords  some  additional  evidence 
in  support  of  the  origin  of  the  Odobenidae  in  the  North  Pacific  Ocean  rather  than  in 
the  North  Atlantic. 

I  take  this  opportunity  to  express  my  indebtedness  to  Dr.  John  C. 
Merriam  for  the  advice  and  assistance  he  has  given  me  in  the  study  of 
the  fossil  Pinnipedia;  and  also  to  Dr.  Chester  Stock  for  help  along  the 
same  lines.  The  drawings  used  in  this  paper  were  made  by  Mrs. 
Freida  Abernathy. 

Acknowledgment  is  made  here  to  Dr.  Joseph  Grinnell,  director  of 
the  Museum  of  Vertebrate  Zoology,  and  Mr.  Gerrit  S.  Miller  Jr., 
United  States  National  Museum,  for  the  loan  of  skeletons  of  living 
pinnipeds  for  comparison. 

Tarsus. 

Calcaneum  possesses  a  rounded  and  produced  greater  process.  Astragalus  appar¬ 
ently  lacks  the  external  prolongation  of  the  body,  while  the  fibular  facet  is  extended 
distally  on  the  neck.  There  is  a  reduced  astragalo-cuboid  contact.  The  navicular  is  of 


Fig.  3. — Calcaneum  of  Eumetopias  jubata  (Schreber),  No.  4112,  Mus.  Vert. 

Zool.,  X0.5.  Ano  Nuevo  Island,  off  San  Mateo  County,  California. 
a,  distal  view;  b,  plantar  view;  c,  tibial  view. 


Fig.  4. — Calcaneum  of  Pontolis  cf.  magnus,  No.  24070,  Mus.  Palaeo.,  Univ. 

Calif.,  X0.5.  Exposures  on  south  side  of  Soledad  Canyon,  San  Diego 
County,  California,  a,  distal  view;  b,  plantar  view;  c,  tibial  view. 


large  proportions;  the  plantar  tuberosity  is  directed  to  the  tibial  side.  Calcanear  facet 
on  cuboid  is  somewhat  flattened  and  slopes  but  slightly  upward  from  fibular  side;  the 
tuberosity  of  the  cuboid  is  restricted  to  fibular  half  of  plantar  face.  Ectocuneiform  is 
prismatic,  its  plantar  aspect  prolonged  into  a  blunt  vertical  hook  and  lacking  a  proxi- 


102  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast . 


mal  facet  of  tibial  face.  Mesocuneiform  is  twisted  toward  the  tibial  side  on  plantar 
half,  with  no  proximal  facet  on  fibular  surface.  Entocuneiform  is  prismatic,  with 
V-shaped  proximal  facet  for  distal  surface  of  the  navicular.  Sesamoid  is  irregularly 
cone-shaped.  Metatarsals  are  long  and  robust,  with  proximal  ends  expanded,  and 
possessing  well-defined  facets  for  articulation  with  tarsal  bones. 


Fig.  5. — Posterior  view  of  calcaneum,  astragalus,  and  navicular  of  Eumetopias  jubata 
(Schreber)  in  position,  No.  4112,  Mus.  Vert.  Zool.,  X0.5.  Ano  Nuevo  Island, 
off  San  Mateo  County,  California. 

Fig.  6. — Posterior  view  of  calcaneum,  astragalus,  and  navicular  of  Pontolis  cf.  magnus, 
in  position,  Nos.  24070,  24071,  and  24072,  Mus.  Palaeo.,  Univ.  Calif.,  X0.5. 
Exposures  on  south  side  of  Soledad  Canyon,  San  Diego  County,  California. 

Calcaneum. 

As  in  other  pinnipeds,  the  calcaneum  was  undoubtedly  the  largest  bone  of  the 
tarsus.  Inasmuch  as  the  proximal  portion  is  missing,  its  proportions  and  relations  with 
the  astragalus  can  be  surmised  only  by  comparison  with  the  same  bones  of  Eumetopias 
jubata  (fig.  5)  and  of  Odobenus  divergens.  However,  in  some  respects  this  particular 
tarsal  element  exhibits  a  closer  affinity  to  Odobenus  than  to  Eumetopias. 

Only  the  outlines  of  the  peroneal  tubercle  can  be  distinguished,  though  in  position 
it  is  very  similar  to  Eumetopias  and  Odobenus.  This  tubercle  is  considerably  mutilated, 
owing  to  the  fracture  of  the  nodule  and  the  subsequent  loss  of  the  adjoining  portion. 
The  groove  which  lodges  the  ligament  for  the  extensor  muscles  is  shallow  and  relatively 
smooth,  and  not  rugose  as  in  Eumetopias. 

From  an  inferior  view  the  relative  proportions  of  the  calcaneum  of  this  Pliocene 
pinniped  (fig.  4a),  as  compared  with  the  living  genus  Eumetopias  (fig.  3a),  are  best 
revealed.  In  the  latter,  the  articular  facet  for  the  cuboid  has  its  longest  diameter 
extending  from  fibular  to  tibial  side,  while  in  this  fossil  bone  the  longest  axis  is  just 
the  reverse — that  is,  from  the  dorsal  to  the  plantar  side. 

The  fibular  face  of  the  calcaneum  of  Eumetopias  (fig.  36)  is  slightly  arcuate.  The 
plantar  margin  of  the  sustentacular  facet  is  more  rounded  and  less  flaring  than  in  this 
Pliocene  fossil  (fig.  46).  In  this  respect  the  fossil  specimen  resembles  that  of  Odobenus. 
On  the  tibial  surface  (fig.  4c)  is  the  basal  portion  of  the  greater  process  for  articulation 
with  the  ectal  facet  of  the  astragalus,  and  below  this,  separated  by  the  groove  for  the 
interosseous  ligament,  is  an  extensive  subtriangular  sustentacular  facet  for  articulation 
with  the  corresponding  facet  on  the  astragalus.  The  distal  portion  of  the  greater 
process  is  more  produced  and  more  rounded  than  same  process  on  calcaneum  of 
Eumetopias  (fig.  3c). 


103 


Structure  of  a  Flipper  of  a  Pliocene  Pinniped. 

There  is  a  peculiar  modification  of  the  greater  process  of  the  calcaneum  which  favors 
the  assumption  that  the  ectal  facet  of  the  astragalus  was  considerably  reduced.  The 
distal  portion  of  the  greater  process  is  greatly  produced,  so  much  so  that,  when  the 
sustentacular  facet  of  the  astragalus  is  rotated  on  the  corresponding  articular  surface 
on  tibial  face  of  the  calcaneum,  the  greater  process  of  the  calcaneum  rests  in  the  groove 
of  the  astragalus,  which  in  Eumetopias  serves  for  the  reception  of  the  interosseous 
ligament.  This  peculiar  articulation  is  impossible  in  either  Eumetopias  or  Odobenus, 
for  the  distal  portion  of  the  greater  process  of  the  calcaneum  is  neither  rounded  nor 
produced,  but  instead  is  flattened. 


Fig.  7. — Astragalus  of  Eumetopias  jubata  (Schreber),  No.  4112,  Mus. 

Vert.  Zool.,  X0.5.  Ano  Nuevo  Island,  off  San  Mateo 
County,  California,  a,  distal  view;  b,  plantar  view;  c,  fib- 
ular  view. 


The  lesser  process  is  relatively  longer  and  narrower  than  in  Eumetopias,  and  slightly 
resembles  that  of  Odobenus.  The  groove  for  the  interosseous  ligament  is  narrow  and 
deep  as  in  Eumetopias,  forming  a  considerable  sinus  between  the  articular  surfaces 
when  the  astragalus  and  calcaneum  are  in  position. 


Measurements  of  calcaneum  {in  millimeters). 


Fig.  8. — Astragalus  of  Pontolis  cf.  magnus,  No.  24071,  Mus.  Palaeo.,  Univ. 

Calif.,  X0.5.  Exposures  on  south  side  of  Soledad  Canyon,  San  Diego 
County,  California,  a,  distal  view;  6,  plantar  view;  c,  fibular  view. 


Pontolis 
magnus? 
No.  24070. 

Eumetopias 

jubata. 

No.  4112. 

Greatest  dorso-plantar  diameter  of  distal  end . 

76 

59 

Greatest  tibio-fibular  diameter  of  distal  end . 

67 

37 

Greatest  dorso-plantar  diameter  of  sustentacular  facet . 

50 

35 

Greatest  dorso-plantar  diameter  of  cuboid  facet . 

38 

28 

104  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


Astragalus. 

On  the  whole  the  astragalus  is  considerably  larger  than  the  same  element  in  the 
tarsus  of  either  Eumetopias  or  Mirounga.  In  size,  the  head  of  the  astragalus 
approaches  that  of  Odobenus ,  though  in  other  respects  it  is  quite  different.  The  most 
characteristic  feature  is  the  presence  of  an  exceedingly  large  fibular  facet  (fig.  2),  with  a 
correlated  reduction  of  the  body  on  the  external  side.  The  reduced  external  pro¬ 
longation  of  the  body,  together  with  what  appears  to  be  a  rather  prominent  internal 
projection,  is  most  unusual  for  an  otarid  and  reminds  one  at  once  of  the  phocids,  more 
especially  Mirounga  angustirostris.  This  specimen  lacks  the  major  portion  of  the  body 
with  its  trochlea.  That  portion  of  the  astragalus  is  undoubtedly  present  in  the 
adjoining  part  of  the  nodule  which  was  not  found  at  the  time  the  present  specimen  was 
collected.  The  weight  of  the  body  was  presumably  transmitted  to  this  astragalus, 
largely  by  the  tibia,  as  in  other  pinnipeds,  though  it  is  also  quite  certain  from  the  larger 
fibular  facet  that  the  fibula  as  well  had  a  considerable  share  in  the  transmission  of  the 
weight. 


Fig.  9. — Navicular  of  Eumetopias  jubata 
(Schreber),  No.4112,  Mus.  Vert.  Zool, 
X  0.5.  Ano  Nuevo  Island,  off  San 
Mateo  County,  California,  a,  proxi¬ 
mal  view;  b,  distal  view. 


The  dorsal  surface  of  the  neck  is  somewhat  flattened,  relatively  short  and  quite  wide, 
with  an  extensive  rugose  area  for  attachment  of  extensor  muscles,  which,  narrowing 
into  a  shallow  groove  on  the  external  side,  separates  the  fibular  facet  from  the  navicular 
facet. 

Fig.  10. — Navicular  of  Pontolis 
cf.  magnus  No.  24072, 
Mus.  Palaeo.,  Univ.  Calif., 
X0.5.  Exposures  on  south 
side  of  Soledad  Canyon, 
San  Diego  County,  Cali¬ 
fornia.  a,  proximal  view; 

6,  distal  view. 

It  is  interesting  to  note  that  the  head  (fig.  8a)  sets  more  obliquely  on  the  body  than 
it  does  in  Eumetopias  (fig.  7a).  Furthermore,  the  neck  is  so  twisted  that  the  long  axis 
of  the  head  is  directed  obliquely  backward  internally,  while  in  Eumetopias  the  same 
axis  is  directed  more  dorso-ventrally.  The  distal  surface  (fig.  8a)  is  limited  to  the 
front  of  the  head;  in  outline  it  is  almost  kidney-shaped,  the  main  diameter  running 
obliquely  from  the  tibial  side  dorsally  to  the  fibular  side  ventrally.  The  surface  is 
convex  in  both  directions  and  serves  as  the  articular  surface  for  the  proximal  facet  of 
the  navicular.  There  is  also  present  a  small  facet  for  articulation  with  corresponding 
facet  on  cuboid.  In  this  Pliocene  pinniped  the  long  axis  of  the  head  rests  rather 
obliquely  in  the  extero-internal  axis  of  the  navicular  (fig.  2a),  while  in  Eumetopias  the 
long  axis  rests  nearly  dorso-ventrally  (fig.  1). 

The  fibular  facet  (fig.  2b)  is  very  large  and  extends  distally  almost  to  the  navicular 
facet,  being  separated  from  it  by  the  shallow  extensor  groove.  The  fibular  articulation 
is  more  oblique  than  in  Eumetopias  (fig.  1).  In  contrast  with  other  known  pinnipeds, 
this  fibular  facet  is  broad,  rather  elongate,  somewhat  concave  distally,  with  a  promi¬ 
nent  crest  between  it  and  the  tibial  surface,  and  is  accompanied  by  a  reduction  of 
the  external  prolongation  of  the  body  of  the  astragalus. 


Structure  of  a  Flipper  of  a  Pliocene  Pinniped. 


105 


The  plantar  surface  (fig.  86)  is  not  as  sharply  defined  as  in  Eumetopias  (fig.  76). 

The  fibular  surface  of  the  head  (fig.  8c)  is  irregular  in  outline,  and  is  occupied  by  a 
large  triangular  articular  facet  for  the  sustentacular  facet  of  the  calcaneum.  The  groove 
invading  the  sustentacular  facet  from  the  plantar  side  is  more  like  that  observed  in 
Odobenus,  for  in  the  latter,  as  well  as  in  Mirounga,  this  groove  is  continuous  dorsally 
with  the  groove  for  the  interosseous  ligament.  In  comparing  the  astragalus  of  this 
Pliocene  pinniped  with  the  astragalus  of  Eumetopias,  it  was  observed  that  there  is  a 
similar  groove  invading  the  sustentacular  facet  in  both,  though  it  is  much  shorter  in 
the  fossil.  In  contrast  with  Eumetopias  (fig.  7c),  the  sustentacular  facet  of  this 
astragalus  was  apparently  separated  from  the  ectal  facet  by  the  deep  groove  for  the 
interosseous  ligament.  The  groove  for  this  ligament  is  much  deeper  and  relatively 
broader  than  in  Eumetopias  and  is  bounded  on  either  side  by  poorly  marked  crests, 
though  no  astragalar  foramen  is  present. 


Measurements  of  astragalus  ( in  millimeters). 


Pontolis 

Eumetopias 

magnus? 

jubata. 

No.  24071. 

No.  4112. 

Greatest  dorso-plantar  diameter  of  head . 

33 

26.5 

Greatest  tibio-fibular  diameter  of  head . 

58 

48 

Navicular. 

The  navicular  is  extraordinarily  long,  relatively  narrow,  and  quite  thin.  Its  pro¬ 
portions  are  quite  different  from  the  same  bone  in  Eumetopias,  though  differences 
in  relative  depth  and  breadth  constitute  the  chief  features.  Its  transverse  or  tibio¬ 
fibular  diameter  is  almost  twice  the  vertical  or  dorso-plantar  diameter,  while  in 
Eumetopias  these  two  measurements  are  more  nearly  equal.  In  some  details,  especially 
the  distal  face  with  articular  facets  for  the  cuneiforms,  the  navicular  is  quite  similar. 
On  the  plantar  face  is  a  prominent  tuberosity  (fig.  106),  which  is,  however,  directed 
toward  the  tibial  side  and  not  towards  the  fibular  as  in  Eumetopias  (fig.  96).  The 
articular  facet  for  the  astragalus  (fig.  10a)  is  strongly  concave  with  a  sudden  upward 
curvature  on  both  tibial  and  fibular  sides  of  the  navicular. 


d 


Fig.  11. — Cuboid  of  Eumetopias  jubata  (Schreber),  No.  4112,  Mus.  Vert.  Zool., 

X0.5.  Ano  Nuevo  Island,  off  San  Mateo  County,  California, 
a,  plantar  view;  b,  tibial  view;  c,  dorsal  view;  d,  distal  view. 

On  the  fibular  and  plantar  borders  of  the  navicular  there  is  a  relatively  small  facet, 
as  compared  with  same  facet  in  recent  otarids,  which  articulates  with  corresponding 
facets  on  tibial  face  of  cuboid.  This  fibular  facet  is  quadrangular  in  Odobenus,  long 
and  narrow  in  both  Eumetopias  and  Mirounga,  while  it  is  almost  triangular  in  this 
fossil  specimen. 

In  appearance  the  distal  surface  (fig.  106),  with  the  extensive  rugose  area  which 
restricts  the  facets  for  cuneiforms  from  plantar  half  of  this  face,  most  resembles  that  of 


106  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


Eumetopias  (fig.  96).  In  this  respect  the  fossil  is  quite  unlike  either  Odobenus  or 
Mirounga,  for  in  these  forms  the  facets  cover  the  entire  distal  face.  In  this  fossil 
specimen  there  are  three  facets,  more  or  less  distinct,  though  continuous  with  one 
another;  the  largest  lies  at  the  dorsal  and  tibial  corner.  It  is  somewhat  curved  in 
outline  and  serves  as  the  articular  facet  for  entocuneiform,  although  it  is  not  separated 
from  the  adjoining  slightly  concave  facet  for  mesocuneiform.  The  third  facet  lies  on 
the  dorso-fibular  border,  just  below  the  preceding,  from  which  it  is  separated  by  an 
elevated  line. 


sures  on  south  side  of  Soledad  Canyon,  San  Diego  County,  California,  a,  plantar 
view;  b,  tibial  view;  c,  dorsal  view;  d,  distal  view. 


The  tibial  corners  are  rounded  off.  About  half  of  the  distal  face,  or  that  area  lying 
between  the  plantar  tuberosity  and  the  facets  for  the  cuneiforms,  is  depressed  and 
roughened  for  the  interosseous  ligament. 


Measurements  of  navicular  {in  millimeters). 


Pontolis 

Eumetopias 

magnus? 

jubata. 

No.  24072. 

No.  4112. 

Dorso-plantar  diameter . 

44 

44 

Tibiofibular  diameter . 

72 

52 

Greatest  vertical  diameter . 

30 

25 

Cuboid. 

The  cuboid  is  large,  equaling  in  size  that  of  Odobenus.  The  reduction  of  the  astrag- 
alo-cuboid  contact  is  an  important  feature  of  the  tarsus  of  this  Pliocene  pinniped 
and  in  this  point  it  differs  from  either  Odobenus  or  Eumetopias.  In  all  known  pinnipeds 
the  astragalo-cuboid  contact  is  relatively  large,  the  astragalus  being  more  or  less 
supported  by  the  cuboid.  It  is  doubtful  if  the  position  of  the  cuboid  in  the  tarsus  of 
this  Pliocene  pinniped  afforded  as  much  support  to  the  astragalus  as  it  does  in  living 
otarids. 

Posteriorly  this  cuboid  (fig.  12a)  differs  from  the  same  tarsal  element  of  Eumetopias 
(fig.  11a)  in  the  reduction  of  the  tuberosity.  In  the  latter,  this  tuberosity  extends 
entirely  across  the  plantar  face,  while  in  this  Pliocene  form  it  is  restricted  to  the  fibular 
half  of  the  face. 

Proximally  the  cuboid  exhibits  a  somewhat  flattened  three-sided  articular  facet, 
strongly  deflected  externally.  In  all  other  otarids  the  facet  for  the  calcaneum  is 
decidedly  oblique,  forming  a  sharp  angle  with  the  facet  for  the  astragalus.  The  tibio- 
plantar  angle  of  this  facet  is  quite  sharp,  the  plantar  border  is  nearly  straight,  while 
the  dorso-fibular  border  is  evenly  convex.  The  external  tuberosity  is  considerably 


Structure  of  a  Flipper  of  a  Pliocene  Pinniped. 


107 


produced  as  in  Eumetopias,  its  proximal  articular  surface  being  cut  off  from  the 
calcanear  facet  by  an  elevated  line. 

On  the  tibial  face  (fig.  126)  is  a  large  proximal  facet  with  its  greatest  axis  proximo- 
distal,  and  relatively  broad  transversely.  The  superior  portion  of  this  facet  articulates 
with  the  corresponding  facet  of  the  navicular  and  the  inferior  narrower  portion  with 
the  ectocuneiform.  There  is  also  a  small  dorsal  facet  on  the  distal  border  of  the  cuboid 
for  articulation  with  the  lower  anterior  fibular  facet  of  the  ectocuneiform.  This  facet 
in  Eumetopias  (fig.  116)  is  reduced  to  a  mere  vestige.  The  pit  for  the  insertion  of  the 
interosseous  ligament  is  relatively  larger  and  deeper  than  in  either  Odobenus  or 
Eumetopias. 


Fig.  13. — Ento cuneiform  of  Eumetopias  jubata 
(Schreber),  No.  4112,  Mus.  Vert.  Zool., 
X0.5.  Ano  Nuevo  Island,  off  San  Mateo 
County,  California,  o,  distal  view;  b,  tibial 
view;  c,  fibular  view. 


The  dorsal  and  fibular  faces  are  more  or  less  continuous  with  one  another.  The 
outstanding  feature  (fig.  12c)  is  a  broad,  rugose,  and  obliquely  situated  groove  for  the 
attachment  of  ligaments  and  flexor  muscles,  which  begins  near  the  plantar  and  proximal 
borders  and  extends  toward  the  dorso-distal  angle. 


Fig.  14. — Entocuneiform 
of  Pontolis  cf.  magnus, 
No.  24074,  Mus. 
Palaeo.,  Univ.  Calif., 
X0.5.  Exposures  on 
south  side  of  Soledad 
Canyon,  San  Diego 
County,  California, 
a,  distal  view;  b,  tibial 
view ;  c,  proximal  view. 


Distally  there  is  a  curved  articular  surface  (fig.  12 d)  for  the  bases  of  the  fourth  and 
fifth  metatarsals,  nearly  U-shaped  in  outline,  with  an  abrupt  downward  slope  on  the 
dorsal  and  tibial  borders.  The  facet  on  the  fibular  border  to  articulate  with  the  base 
of  the  fifth  metatarsal  is  strongly  concave,  though  it  is  deflected  upward  and  ventrally. 
All  the  borders  of  the  distal  face  are  sharp. 


Measurements  of  cuboid  {in  millimeters) . 


Pontolis 

Eumetopias 

magnus? 

jubata. 

No.  24073. 

No.  4112. 

Greatest  median  dorso-plantar  diameter . 

36 

36 

Greatest  tibio-fibular  diameter . 

45 

35 

Greatest  proximo-distal  diameter . 

61 

48 

Entocuneiform. 

A  characteristic  feature  of  this  fossil  entocuneiform,  in  addition  to  its  prismatic 
appearance,  is  the  roughly  V-shaped  proximal  facet.  The  dorsal  surface  is  somewhat 
flattened  and  depressed.  Centrally,  an  extensive  concavity,  strongly  rugose,  exists  for 
the  attachment  of  a  muscle.  It  differs  markedly  from  the  same  element  in  the  tarsus 


108  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


of  Eumetopias  by  the  presence  of  a  strong  emargination  on  the  proximo-fibular  angle 
for  the  corresponding  articular  surface  on  the  mesocuneiform. 

With  the  exception  of  the  proximal  facet,  the  close  resemblance  of  this  tarsal 
element  to  the  corresponding  one  in  Odobenus  is  very  striking.  The  distal  facet  is  more 
nearly  like  that  of  the  walrus  than  that  of  any  other  pinniped,  while  the  similarity 
in  the  strong  emargination  of  the  dorso-proximal  corner  of  the  fibular  face  to  serve  as 
an  articular  surface  for  the  mesocuneiform,  in  both  forms,  is  undoubtedly  more  than 
a  coincidence.  Other  features  possessed  by  this  fossil  flipper  closely  connect  the 
otarids  with  the  odobenids,  and  possibly  more  remotely  with  the  cystophorids  as 
illustrated  by  Mirounga. 


a 


Fig.  15. — Mesocuneiform  of  Eumetopias  jubata  (Schreber), 
No.  4112,  Mus.  Vert.  Zool.,  X0.5.  Ano  Nuevo  Is¬ 
land,  off  San  Mateo  County,  California,  a,  tibial 
view;  b,  fibular  view. 


The  distal  articular  surface  (fig.  14a)  is  club-shaped,  narrower  near  the  tibial  border 
than  at  dorso-fibular  border;  the  long  axis  runs  obliquely  from  the  fibular  to  the 
tibial  side.  This  facet  is  also  characterized  by  the  strong  convexity  of  the  dorso-fibular 
portion.  This  same  facet  in  Eumetopias  (fig.  13a)  is  more  or  less  triangular,  with  its 
base  lying  on  the  fibular  border  and  its  two  sides  meeting  in  a  rounded  apex  on  the 
tibial  border. 

On  the  tibial  side,  the  entocuneiform  of  this  fossil  pinniped  (fig.  146)  differs  from 
that  of  Eumetopias  (fig.  136)  in  the  shape  of  the  facet  for  the  sesamoid,  in  the  position 
of  the  proximo-plantar  articular  process,  as  well  as  in  the  reduction  of  the  distal 
border.  The  facet  for  the  sesamoid  is  somewhat  quadrangular  in  outline,  with  its 
greatest  diameter  extending  from  the  dorsal  to  the  plantar  side,  and  continuous  with  an 
adjoining  articular  surface  which  projects  over  upon  the  dorsal  face.  The  borders  are 
sharply  defined,  and  below  this  facet  the  surface  is  depressed  and  quite  rugose.  The 
articular  process,  which  in  Eumetopias  lies  on  the  plantar  face,  is  directed  toward  the 
tibial  side  and  elevated  to  the  proximal  border  in  this  fossil  specimen. 


Fig.  16. — Mesocuneiform  of  Pontolis  cf.  magnus,  No.  24075, 
Mus.  Palaeo.,  Univ.  Calif.,  X0.5.  Exposures  on 
south  side  of  Soledad  Canyon,  San  Diego  County, 
California,  a,  tibial  view;  6,  fibular  view. 


The  fibular  surface  presents  a  proximal  and  a  distal  half,  of  which  the  former  is 
nearly  twice  the  size  of  the  latter.  In  Eumetopias  the  two  halves  are  more  nearly 
equal  in  size.  The  plantar  border  of  the  proximal  half  of  this  fossil  entocuneiform  is 
curved  away  from  the  main  axis  and  is  directed  to  the  sole  of  the  foot.  The  distal 
border  of  the  fibular  face  of  the  entocuneiform  of  Eumetopias  is  squarely  truncate,  and 
is  occupied  by  an  elongate  facet  (fig.  13c)  for  articulation  with  the  corresponding  facet 
on  second  metatarsal.  In  this  fossil  bone  the  distal  border  is  rounded  and  the  facet 
somewhat  reduced  in  extent.  The  facet  for  the  navicular  does  not  extend  down  upon 
the  fibular  face  in  this  fossil  though  it  does  in  Eumetopias. 

The  facet  on  the  proximal  surface  of  the  entocuneiform  for  articulation  with  the 
distal  surface  of  the  navicular  is  nearly  kidney-shaped  in  Eumetopias  (fig.  13c) ;  it  is 
slightly  concave  and  slopes  toward  the  fibular  side.  As  remarked  previously,  this 
same  facet  on  the  fossil  bone  is  roughly  V-shaped  (fig.  14c).  Furthermore,  it  differs 
from  Eumetopias  in  another  important  feature,  in  that  this  facet  lies  more  nearly  in 
a  horizontal  plane,  sloping  but  slightly  toward  the  fibular  side. 


Structure  of  a  Flipper  of  a  Pliocene  Pinniped.  109 


Measurements  of  entocuneiform  (in  millimeters) . 


Pontolis 
magnus? 
No.  24074. 

Eumetopias 

jubata. 

No.  4112. 

Greatest  vertical  diameter . 

48 

41 

Greatest  tibio-fibular  diameter . 

59 

37 

Greatest  dorso-plantar  diameter'.' . 

38 

31 

Greatest  diameter  of  distal  articular  surface . 

43 

34 

Mesocuneiform. 

The  mesocuneiform  is  much  reduced  in  size;  it  is  relatively  smaller  than  same 
element  in  the  tarsus  of  Eumetopias,  though  it  has  a  greater  vertical  diameter  than  in 
the  latter. 

Near  the  proximal  border  of  the  mesocuneiform  of  Eumetopias  (fig.  15a)  lies  a 
quadrangular  articular  facet,  occupying  a  considerable  portion  of  the  tibial  face,  which 
in  turn  serves  as  an  articular  surface  for  the  entocuneiform.  In  this  fossil  bone  (figs. 
2 a  and  16a)  the  proximal  border  is  considerably  produced  and  shows  an  obscure  facet 
for  articulation  with  the  proximo-dorsal  portion  of  the  fibular  surface  of  the  ento¬ 
cuneiform. 

Fig.  17. — Ectocuneiform  of 
Eumetopias  jubata  (Schre- 
ber),  No.  4112,  Mus.  Vert. 

Zool.,  X0.5.  Ano  Nuevo 
Island,  off  San  Mateo 
County,  California.  a, 
fibular  view ;  b,  tibial  view ; 
c,  proximal  view;  d,  distal 
view. 

The  proximal  surface  (fig.  166)  is  occupied  by  a  large  oval  facet  for  articulation 
with  the  corresponding  facet  on  distal  surface  of  the  navicular;  it  is  strongly  concave, 
with  sharply  defined  borders,  and  slopes  toward  the  fibular  side  of  the  tarsus.  On  the 
mesocuneiform  of  Eumetopias  this  same  facet  has  a  more  elongate  dorso-plantar 
diameter  and  is  decidedly  more  flattened. 

A  large,  proximal,  rectangular  facet  for  the  ectocuneiform  (fig.  156)  is  present  on 
the  fibular  face  of  the  mesocuneiform  in  Eumetopias,  though  no  trace  of  the  same  can 
be  found  in  this  fossil  bone  (fig.  166).  Almost  the  entire  fibular  surface  of  this  fossil 
mesocuneiform  is  roughened  for  an  interosseous  ligament,  while  in  Eumetopias  this 
area  is  confined  to  a  narrow  space  between  the  small  dorso-distal  facet  for  the  ecto¬ 
cuneiform  and  the  above-mentioned  rectangular  facet. 

The  distal  surfaces  of  the  mesocuneiforms  of  both  Eumetopias  and  this  fossil  pinni¬ 
ped  are  essentially  the  same,  the  main  difference  being  the  degree  of  concavity, with 
the  latter  exhibiting  a  more  strongly  marked  downward  curvature  on  both  dorsal 
and  plantar  borders.  The  plantar  surface  is  not  produced  distally  as  much  as  in 
Eumetopias  (fig.  15a),  though  in  both  it  is  merely  a  rounded  plantar  border. 


Measurements  of  mesocuneiform  (in  millimeters) . 


Pontolis 
magnus? 
No.  24075. 

Eumetopias 

jubata. 

No.  4112. 

Greatest  dorso-plantar  diameter . 

31 

33 

Greatest  tibio-fibular  diameter . 

20 

14 

Greatest  vertical  diameter . 

25 

20 

110  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


Ectocuneiform. 

In  general  appearance,  the  ectocuneiform  of  this  Pliocene  pinniped  is  quite  similar 
to  the  same  element  in  the  tarsus  of  Eumetopias  jubata.  However,  it  is  more  prismatic, 
one  side  of  the  prism  forming  the  dorsal  surface  and  the  remaining  two  sides  forming 
the  tibial  and  fibular  surfaces,  respectively;  at  the  proximal  and  distal  ends  it  is  cut  off 
obliquely;  the  plantar  aspect  is  produced  into  a  low,  blunt  hook  directed  upwards. 
The  concave  side  of  this  hook  faces  toward  the  fibular  surface,  thus  forming  a  shallow 
groove.  This  same  groove  (fig.  17a)  in  the  ectocuneiform  of  Eumetopias  is  deeper  and 
more  rugose.  It  serves  to  hold  in  place  the  tendon  of  the  peroneus  longus. 


Fig.  18. — Ectocuneiform 
of  Pontolis  cf.  magnus, 
No.  24076,  Mus. 
Paleao.,  Univ.  Calif. 
X0.5.  a,  fibular  view; 
b,  tibial  view;  c,  proxi¬ 
mal  view;  d,  distal 
view. 


The  proximal  facet  (fig.  18a)  on  the  fibular  face  is  subtriangular  in  outline;  it  articu¬ 
lates  with  the  distal  portion  of  an  elongated  facet  near  the  middle  of  the  tibial  sur¬ 
face  of  the  cuboid.  There  is  also  an  oval  facet  on  the  dorso-distal  angle  of  the  fibular 
face  of  the  ectocuneiform  for  articulation  with  the  corresponding  facet  on  the  cuboid. 

On  the  tibial  surface  (fig.  186),  there  are  two  distal  swellings,  one  dorsal  and  the 
other  plantar.  These  swellings  are  separated  by  a  deep  groove  which  is  much  broader 
though  relatively  shallower  than  in  Eumetopias.  No  counterpart  of  the  proximal 
oblong-shaped  facet  on  the  tibial  surface  of  the  ectocuneiform  of  Eumetopias  (fig.  176) 
can  be  found  on  this  fossil  bone. 

The  proximal  surface  (fig.  18c)  is  occupied  by  a  large  shallowly  concave  facet  for 
articulation  with  the  same  facet  on  distal  surface  of  navicular.  The  corresponding 
facet  on  ectocuneiform  of  Eumetopias  (fig.  17c)  is  more  or  less  flattened,  though  it  is 
nearly  quadrangular  and  not  triangular  in  outline  as  on  the  fossil  bone. 

The  distal  surface  (fig.  1 8d)  is  similar  in  outline  to  that  of  the  proximal  surface 
with  the  exception  of  a  deep  indentation  on  the  tibial  border.  The  plantar  half  of  this 
face  is  lost.  The  articular  surface  of  the  dorsal  half  is  strongly  concave,  much  more  so 
than  in  Eumetopias  (fig.  17 d). 


Measurements  of  ectocuneiform  ( in  millimeters). 


Pontolis 
magnus? 
No.  24076. 

Eumetopias 

jubata. 

No.  4112. 

Greatest  dorso-plantar  diameter . 

48 

38 

Greatest  tibio-fibular  diameter . 

25 

18 

Greatest  vertical  diameter . 

32 

24 

Sesamoid. 

The  sesamoid  of  this  Pliocene  pinniped  is  quite  different  from  that  of  Eumetopias. 
The  sesamoid  of  Eumetopias  (fig.  196)  is  rhomboid  in  outline  and  so  placed  on  the 
tibial  side  of  the  entocuneiform  that  the  pointed  end  is  directed  distally.  The  longest 
diameter  of  the  articular  facet  (fig.  19a)  for  corresponding  facet  on  the  entocuneiform 
is  proximo-distal.  However,  the  sesamoid  of  this  fossil  tarsus  has  the  form  of  an 


Structure  of  a  Flipper  of  a  Pliocene  Pinniped. 


Ill 


irregular  cone  (fig.  206),  while  the  longest  diameter  of  the  articular  facet  (fig.  20a) 
is  dorso-plantar. 


Fig.  19. — Sesamoid  of  Eumetopias  jubata  (Schreber),  No.  4112,  Mus. 

Vert.  Zool.,  X0.5.  Ano  Nuevo  Island,  off  San  Mateo 
County,  California.  a,  fibular  view;  b,  tibial  view. 
Fig.  20. — Sesamoid  of  Pontolis  cf.  magnus,  No.  24077,  Mus. 

Palaeo.,  Univ.  Calif.,  X0.5.  Exposures  on  south  side 
of  Soledad  Canyon,  San  Diego  County,  California,  a, 
fibular  view;  b,  tibial  view. 


Measurements  of  sesamoid  {in  millimeters). 


Pontolis 
magnus? 
No.  24077. 

Eumetopias 

jubata. 

No.  4112. 

Dorso-plantar  diameter . 

26 

29 

Proximo-distal  diameter . 

21 

39 

Tibio-fibular  diameter . 

18.5 

19 

First  Metatarsal. 

The  first  metatarsal  (fig.  21  d)  of  this  fossil  pinniped  is  quite  unlike  that  of  Eume¬ 
topias.  It  is  larger  than  all  the  other  metatarsals,  both  with  respect  to  length  and  to 
relative  proportions.  The  shaft  of  this  metatarsal  is  roughly  three-sided,  the  dorsal 
border  forming  the  base,  the  fibular  and  tibial  borders  meeting  in  a  rounded  apex  at  the 
plantar  angle  to  form  the  sides.  On  the  tibio-plantar  face  (fig.  21e)  are  two  proximal 
swellings,  one  dorsal  and  the  other  plantar;  these  swellings  are  separated  by  a  broad 
groove.  The  proximal  end  is  occupied  by  a  concave  facet  (fig.  21/)  which  is  strongly 
curved  upwards  on  the  dorsal  and  plantar  borders  and  slopes  towards  the  fibular  side. 
It  articulates  with  the  corresponding  facet  on  distal  surface  of  entocuneiform. 

Since  only  the  proximal  end  of  the  first  metatarsal  of  this  flipper  is  preserved,  it  is 
fortunate  that  a  second  great  toe  was  found  in  southern  California,  and  presumably 
in  the  same  horizon,  by  Mr.  Howell  Gester.  This  specimen,  No.  24083  (fig.  21  g), 
appears  to  belong  to  a  somewhat  older  individual.  The  differences  are  especially 
noticeable  when  the  proximal  ends  are  compared  with  each  other.  In  this  second 
specimen  there  is  a  greater  development  of  the  proximal  swellings  or  tuberosities  on 
the  tibio-plantar  face,  and  accompanied  by  a  narrowing  of  the  intervening  groove.  The 
same  changes  occur  during  growth  in  Eumetopias ,  the  oldest  individuals  possessing  the 
most  prominent  tuberosities.  Otherwise  the  proximal  end  (fig.  2 If)  is  very  similar  to 
the  corresponding  portion  (fig.  21/)  of  the  above  described  metatarsal.  The  main 
feature  wherein  it  differs  from  Eumetopias  lies  in  the  modification  of  the  proximal 
facet;  in  Eumetopias  (fig.  21c)  this  facet  is  shallowly  concave,  its  fibular  and  tibial 
borders  slightly  upturned,  while  the  articular  surface  itself  slopes  towards  both  dorsal 
and  plantar  faces.  The  facet  is  roughly  four-sided,  with  slight  emargination  on  the 
plantar  side.  In  this  fossil  metatarsal  (fig.  21f),  the  facet  is  roughly  three-sided  and  is 
constricted  medially  on  the  dorsal  and  tibial  borders.  The  plantar  border  of  this 
facet  is  more  strongly  upturned  than  the  dorsal. 


112  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


del 


Fig.  21. — a,  b,  c:  First  metatarsal  of  Eumetopias  jubata  (Schreber),  No.  4112,  Mus.  Vert. 

Zool.,  X0.5.  Ano  Nuevo  Island,  off  San  Mateo  County,  California,  a,  plantar 
view;  b,  dorsal  view;  c,  proximal  view,  d,  e,  f:  First  metatarsal  of  Pontolis  cf. 
magnus,  No.  24078,  Mus.  Palaeo.,  Univ.  Calif.,  X0.5.  Exposures  on  south  side 
of  Soledad  Canyon,  San  Diego  County,'  California,  d,  fibular  view;  e,  tibio- 
plantar  view;  /,  proximal  view,  g,  h,  i :  First  metatarsal  of  Pontolis  cf.  magnus , 
No.  24083,  Mus.  Palaeo.,  Univ.  Calif.,  X0.5.  Sandy  shale  formation  in  Section 
27,  Township  4  North,  Range  15  West,  near  section  line  directly  west  of  2,006’ 
elev.  hill,  Los  Angeles  County,  California,  g,  tibial  view;  h,  fibular  view;  i, 
proximal  view. 


Measurements  of  first  metatarsal  {in  millimeters) . 


Pontolis 
magnus? 
No.  24078. 

Pontolis 
magnus? 
No.  24083. 

Eumetopias 

jubata. 

No.  4112. 

Length . 

X 

165 

127 

Dorso-plantar  diameter  of  head . 

38 

41 

23 

Tibio-fibular  diameter  of  head . 

43 

48 

41 

Dorso-plantar  diameter  of  distal  end . 

X 

28 

17.5 

Tibio-fibular  diameter  of  distal  end . 

X 

27 

28 

Structure  of  a  Flipper  of  a  Pliocene  Pinniped.  113 

The  fibular  margin  of  the  shaft  is  slightly  arcuate.  The  entire  bone  tapers  toward 
the  distal  end.  The  distal  articular  surface  is  rounded.  A  shallow  depression  is  pres¬ 
ent  on  the  fibular  face,  and  a  slight  tuberosity  on  the  tibial. 


Second  Metatarsal. 

The  shaft  is  strongly  bent  toward  the  tibial  side.  The  tibial  surface  (fig.  23 a)  pos¬ 
sesses  along  the  proximal  edge  an  extensive  facet  for  articulation  with  distal  portion 
of  fibular  articular  surface  of  the  entocuneiform.  It  lacks  the  lower  proximal  process 
which  is  present  in  Eumetopias  (fig.  22a),  for  in  this  fossil  flipper  there  is  no  articulation 
with  the  first  metatarsal,  as  in  the  recent  otarids.  The  plantar  surface  is  relatively 
broad  and  not  narrowing  to  a  sharp  crest  proximally,  as  in  Eumetopias. 


Fig.  22. — Second  metatarsal  of  Eumetopias  jubata  (Schreber),  No.  4112,  Mus. 

Vert.  Zool.,  X0.5.  Ano  Nuevo  Island,  San  Mateo  County,  California. 
a,  tibial  view;  b,  fibular  view. 

Fig.  23. — Second  metatarsal  of  Pontolis  cf.  magnus,  No.  24079,  Mus.  Palaeo., 
Univ.  Calif.,  X0.5.  Exposures  on  south  side  of  Soledad  Canyon,  San 
Diego  County,  California,  a,  tibial  view;  b,  fibular  view. 


On  the  fibular  surface  (fib.  236)  there  is  a  strongly  concave  facet  on  the  proximal  end 
near  the  dorsal  border  for  the  reception  of  an  articular  swelling  on  the  tibial  surface 
of  the  third  metatarsal,  and  with  which  it  interlocks.  Above  this  concave  facet  is  an 
oblique  articular  surface  for  the  distal  end  of  the  tibial  surface  of  the  ectocuneiform. 

The  outline  of  the  head  is  essentially  the  same  as  that  exhibited  by  the  second 
metatarsal  of  Eumetopias ,  though  the  facets  differ  considerably.  In  Eumetopias,  the 
main  facet  for  the  mesocuneiform  is  shallowly  concave  with  elevated  margins  on  the 
tibial  and  fibular  sides.  In  this  fossil  specimen  the  facet  is  somewhat  flattened, 
meeting  the  proximal  margin  of  the  facet  for  the  ectocuneiform  in  a  sharp  angle  and 
sloping  toward  the  tibial  face. 


Measurements  of  second  metatarsal  (in  millimeters). 


Pontolis 

Eumetopias 

magnus? 

jubata, 

No.  24079. 

No.  4112. 

Dorso-plantar  diameter  of  head . 

36 

32.5 

Tibio-fibular  diameter  of  head . 

24 

17.5 

......  ,  , . 

114  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 

Third  Metatarsal. 

The  head  of  the  third  metatarsal  is  very  large,  relatively  heavy,  and  more  expanded 
than  the  head  of  the  second  metatarsal.  The  shaft  is  large  and  is  twisted  toward  the 
tibial  side.  Notwithstanding  the  larger  size  of  this  metatarsal,  it  is  quite  similar,  in 
many  respects,  to  the  same  bone  in  the  flipper  of  Eumetopias .  The  chief  modifications 
exhibited  by  Eumetopias  are  the  reduction  of  the  interlocking  process  for  the  second 
metatarsal  on  the  tibial  face  (fig.  24a)  and  the  constriction  of  the  groove  separating  the 
facets  on  dorsal  and  plantar  processes  of  the  fibular  face  (fig.  24c). 

On  the  tibial  surface  of  the  head  (fig.  24a)  of  this  fossil,  the  main  facet  for  second 
metatarsal  is  of  an  interlocking  nature.  It  is  situated  on  a  large  eminence  and  fits  into 
a  corresponding  groove  on  the  fibular  face  of  the  head  of  the  second  metatarsal,  as 
already  described. 


Fig.  24. — Third  metatarsal  of  Eumetopias  jubata  (Schreber),  No.  4112,  Mus.  Vert. 

Zool.,  X0.5.  Ano  Nuevo  Island,  off  San  Mateo  County,  California, 
a,  tibial  view;  b,  proximal  view;  c,  fibular  view. 

Fig.  25. — Third  metatarsal  of  Pontolis  cf.  magnus,  No.  24080,  Mus.  Palaeo., 
Univ.  Calif.,  X0.5.  Exposures  on  south  side  of  Soledad  Canyon,  Cali¬ 
fornia.  a,  tibial  view;  b,  proximal  view;  c,  fibular  view. 


The  facet  for  the  ectocuneiform  on  the  proximal  surface  (fig.  25 b)  is  somewhat 
crescentic  in  outline,  with  fibular  margin  deeply  emarginated,  and  sharply  defined. 
The  plantar  half  of  this  facet  slopes  from  the  fibular  margin  to  the  tibial,  while  the 
dorsal  half  slopes  two  ways,  being  continuous  externally  with  the  dorsal  fibular  facet 
and  internally  with  the  dorsal  tibial  facet. 

The  fibular  surface  of  the  head  (fig.  25c)  has  two  facets  for  the  head  of  the  fourth 
metatarsal,  which,  however,  are  not  of  an  interlocking  nature.  The  largest  one  of 
these  is  situated  on  a  process  near  the  dorsal  face.  It  is  nearly  quadrangular  and  is 
shallowly  concave,  while  the  smaller  facet  on  plantar  process  is  more  or  less  flattened. 
The  two  facets  are  separated  by  a  broad  concavity. 


Structure  of  a  Flipper  of  a  Pliocene  Pinniped.  115 


Measurements  of  third  metatarsal  (in  millimeters). 


Pontolia 

Eumetopias 

magnus? 

jubata, 

No.  24080. 

No.  4112. 

Dorso-plantar  diameter  of  head . 

42 

32  ' 

Tibio-fibular  diameter  of  head . 

26.5 

17.5 

Fourth  Metatarsal. 

The  fibular  surface  (fig.  27a)  is  so  badly  defaced  that  an  accurate  description  is 
impossible.  There  is,  however,  an  articular  strip  for  the  fifth  metatarsal  which  extends 
along  the  proximal  edge  and  which  is  almost  complete  except  for  the  plantar  border. 
The  proximal  facet  on  the  dorsal  border  for  articulation  with  corresponding  facet  on 
fifth  metatarsal  is,  however,  much  narrower  than  in  Eumetopias  (fig.  27a). 


Fig.  26. — Fourth  metatarsal  of  Eumetopias  jubata  (Schreber),  No.  4112,  Mus.  Vert. 

Zool.,  X0.5.  Ano  Nuevo  Island,  off  San  Mateo  County,  California. 
a,  fibular  view;  b,  proximal  view;  c,  tibial  view. 

Fig.  27. — Fourth  metatarsal  of  Pontolis  cf.  magnus,  No.  24081,  Mus.  Palaeo., 

Univ.  Calif.,  X0.5.  Exposures  on  south  side  of  Soledad  Canyon,  San 
Diego  County,  California,  a,  fibular  view;  b,  proximal  view;  c,  tibial 
view. 

What  remains  of  the  proximal  surface  (fig.  27 h)  indicates  that  in  most  respects  the 
facet  for  the  cuboid  is  similar  in  outline  to  that  possessed  by  the  corresponding  meta¬ 
tarsal  of  Eumetopias  (fig.  266).  There  are,  however,  two  features  of  minor  importance 
which  characterize  the  facet  for  cuboid  on  this  fossil  metatarsal.  The  dorsal  portion 
of  this  facet  is  broader  and  more  evenly  convex,  while  the  dorsal  margin  is  sharply 
defined  and  not  rounded  as  in  Eumetopias.  The  sharp  crest  on  the  plantar  half  of  the 
proximal  surface,  which  marks  the  contact  of  the  facet  for  the  third  metatarsal  and  the 
proximal  facet  for  the  cuboid  in  Eumetopias ,  is  lacking  in  this  fossil.  The  plantar 
portion  of  the  head  is  twisted  on  the  long  axis  of  the  shaft  toward  the  fibular  side  as  in 
Eumetopias. 


116  Tertiary  History  of  Pelagic  Mammals  of  Pacific  Coast. 


Part  of  the  head  on  the  tibial  side  is  missing,  though  a  groove  can  be  distinguished 
(fig.  27 c)  which  is  similar  in  position  to  that  in  Eumetopias  (fig.  26c).  Only  a  small 
part  of  the  proximal  facet  on  the  plantar  margin  remains.  The  dorsal  facet  for  the 
third  metatarsal  does  not  extend  as  far  down  on  tibial  face  as  it  does  in  Eumetopias. 


Measurements  of  fourth  metatarsal  {in  millimeters). 


Pontolis 

Eumetopias 

magnus? 

jubata, 

No.  24081. 

No.  4112. 

Dorso-plantar  diameter  of  head . 

42 

37 

Tibio-fibular  diameter  of  head . 

31 

21 

Fig.  28. — Tibial  view  of  fifth  metatarsal  of  Eume¬ 
topias  jubata  (Schreber),  No.  4112,  Mus. 
Vert.  Zool.,  X0.5.  Ano  Nuevo  Island,  off 
San  Mateo  County,  California. 

Fig.  29. — Tibial  view  of  fifth  metatarsal  of  Pontolis 
ef.  magnus,  No.  24082,  Mus.  Palaeo.,  Univ. 
Calif.,  X0.5.  Exposures  on  south  side  of 
Soledad  Canyon,  San  Diego  County,  Cali¬ 
fornia. 


Fifth  Metatarsal. 

A  typical  feature  of  this  Pliocene  pinniped  is  seen  in  the  flattened  shaft  of  the  fifth 
metatarsal.  It  is  relatively  much  narrower  and  deeper  than  in  any  known  otarid. 
Inasmuch  as  only  a  small  portion  of  the  shaft  (fig.  29)  is  known,  it  is  not  advisable  to 
make  any  comparisons  with  the  same  bone  of  Eumetopias  (fig.  28).  The  following  are 
the  measurements  of  fifth  metatarsal: 


Pontolis  cf.  magnus,  No.  24082:  mm. 

Greatest  dorso-plantar  diameter  of  shaft .  52 

Greatest  tibio-fibular  diameter  of  shaft .  14 

Eumetopias  jubata,  No.  4112: 

Greatest  dorso-plantar  diameter  of  shaft .  34 

Greatest  tibio-fibular  diameter  of  shaft .  17 


INDEX. 

The  following  index  contains  the  names  of  the  families,  genera,  and  species,  which  occur  in  this 
series  of  papers.  Two  kinds  of  type  are  used  for  the  names,  roman  and  italic;  the  former  indi¬ 
cates  valid  names,  the  latter  synonyms.  When  a  species  name  follows  a  genus  name  that  is 
synonymous  with  another  genus  name,  both  the  genus  and  species  names  of  the  combination  are 
italicized,  although  the  species  name  may  be  valid.  Two  kinds  of  type  are  used  in  the  figures 
referring  to  the  pages,  the  heavy-faced  type  indicates  the  pages  on  which  descriptions  may  be 
found. 


PAGE 

acuto-rostrata,  Balaenoptera .  44 

aegyptiacum,  Eotheroides .  65 

Agorophiidae .  37 

alascanus,  Callorhinus,  75,  76,  77,  78,  79,  80,  81 

82,  83,  84,  86,  89,  92 

Allodesmus  kernensis .  71 

angustirostris,  Mirounga . 99,  104 

antwerpiensis,  Thalassocetus .  16 

Arctocephalus,  75,  83,  84,  85,  86,  89,  90,  91,  92, 

94,95 

Arctocephalus  australis.  ..  .84,  86,  89,  90,  99 
australis,  Arctocephalus.  . .  .84,  86,  89,  90,  99 

australis,  Eubalaena .  44 

australis,  Halicore .  67 

Balaena .  49 

mysticetus . 42,  44 

Balaenodon .  1,2 

balaenopsis,  Balaenula .  44 

Balaenoptera .  49 

acuto-rostrata .  44 

borealis . 44 

cortessii .  44 

davidsoni .  71 

gastaldii .  56 

physalus .  44 

ryani .  71 

Balaenula  balaenopsis .  44 

borealis,  Balaenoptera .  44 

byronia,  Otaria .  75 

californianus,  Zalophus .  99 

Callorhinus,  75,  76,  77,  78,  79,  80,  82,  83,  84,  86 

89,  90,  91,  92 

Callorhinus  alascanus,  75,  76,  77,  78,  79,  80,  81, 

82,  83,  84,  86,  89,  92 

capgrandi,  Rytiodus, .  60 

caretti,  Scaldicetus . 7,  8,  16,  34 

carolinensis,  Dinoziphius .  8,9 

catodon,  Physeter . 11, 17,  25,  29 

Cetotherium . 36,  37,  51 

furlongi . 38,  44,  51 

Skull .  39 

Tympanic .  39 

Endocranial  cast .  41 

Mandibles .  41 

Stylohyal .  43 

Cervical  vertebrae .  42 

Dorsal  vertebrae .  44 

Lumbar  vertebrae .  45 

Caudal  vertebrae .  46 

Chevrons .  46 

Ribs .  49 

Scapula .  48 

Humerus .  49 

Radius .  49 

Ulna .  49 

Cetotherium,  gastaldii .  50 

Cetotherium  klinderi . i .  48 


PAGE 

Cetotherium  megalophysum .  51 

Cetotherium  moreni . 39,  40 

rathkii . 36,39,41,51,54 

vandelli . 50,  51 

coronatus,  Palaeodelphis .  6 

cortessii,  Balaenoptera .  44 

crassidens,  Hoplocetus .  5 

cuvieri,  Metaxytherium . 58,63,67 

Cystophorinae .  98 

davidsoni,  Balaenoptera .  71 

davidsonii,  Eschrichitus . 35,41 

Delphininae .  4 

Desmatophoca  oregonensis . 71,  97 

Diaphorocetus . 1,  2,  4,  6,  9,  10,  13,  17 

poucheti. . .  .2,  3,  6,  7,  9,  15,  22 

Dinoziphius .  1,2 

carolinensis .  8,9 

Dioplotherium  manigaulti .  59 

divergens,  Odobenus . 99,  102 

dubusii,  Physeterula . 4,  14,  15 

emmonsi,  Ontocetus . 11, 12,  33 

Eumetopias,  86,  90,  102,  103, 104, 105,  106, 107, 
108,  109,  110,  111,  113,  114,  115,  116 

Eumetopias  jubata . 86,  94,  99,  102,  110 

Eotheroides  aegyptiacum .  65 

Eschrichitus  davidsonii . 35,  41 

Eubalaena  australis .  44 

glacialis . 42, 44 

Eucetus .  1,2 

Eudelphis .  1,2 

mortezelensis .  7 

fasciata,  Phoca .  79 

Felsinotherium .  58 

serresii,  58,  61,  62,  63,  64,  66,  67 

floridanum,  Metaxytherium . 59,  67,  68 

furlongi,  Cetotherium . 38,44,51 

gastaldii,  Balaenoptera .  56 

gastaldii ,  Cetotherium .  50 

glacialis,  Eubalaena . 42,44 

glaucus,  Rhachianectes .  44 

grandis,  Scaldicetus . 6,  7, 16 

Graphiodon .  1,2 

grex,  Xyne .  38 

Halicore . 12,  68,  69 

australis .  67 

Halitherium  schinzi . 58,  67 

hispida,  Phoca .  78 

Homoeocetus .  1,2 

Hoplocetus . 1,2,  5 

crassidens .  5 

obesus .  8,9 

hungaricus,  Mesocetus . 44, 46 

hupschii,  Plesiocetus . . . 36,  51 

Hydrodamalis . 57,  61,  62,  64,  65,  67 

stelleri . 58,  61,  62,  64,  65,  67 

Hypocetus . 1,2, 3 

Idiophyseter . 13, 16, 17 


117 


118 


Index 


PAGE 

Idiophyseter  merriami . 16, 18, 29,  31 

Skull .  18 

Idiorophus . . . 6, 13,  31 

patagonicus . 6,  7,  9,  14,  30,  31 

jordani,  Metaxytherium . 59,  72 

jubata,  Eumetopias . 86,  94,  99,  102, 110 

kernensis,  Allodesmus .  71 

klinderi,  Cetotherium .  48 

kocki,  Miosiren . 58,  67 

Kogia,  13,  18,  19,  20,  22,  24,  25,  26,  27,  28,  30 

Kogiidae .  13 

krahuletzi,  Metaxytherium . 67,  68 

latirostris,  Trichechus . 64,  65,  67,  68,  69 

leccense,  Physodon .  4 

lenis,  Leptophoca .  78 

Leptophoca  lenis .  78 

magnus,  Pontolis . 97,  98 

manigaulti,  Dioplotherium .  59 

marginata,  Neobalaena . 44,46 

mediatlanticus,  Orycterocetus . 11, 13,  31 

mediatlanticus,  Paracetus . 9,  10 

megalophy sum,  Cetotherium .  51 

megalophysum,  Plesiocetus . 51,  52,  53 

Megaptera  miocaena .  72 

nodosa .  44 

versabilis .  72 

merriami,  Idiophyseter . 16,  18,  29,  31 

Mesocetus . 1,  2,  3,  36 

hungaricus . 44,  46 

Metaxytherium,  57,  58,  59,  61,  64,  65,  66,  68,  69 

cuvieri . 58,  63,  67 

floridanum . 59,  67,  68 

jordani . 59,  72 

Skull .  60 

Periotic .  65 

Endocranial  cast .  65 

Dorsal  vertebrae .  66 

Ribs .  69 

Metacarpal .  69 

krahuletzi . 67,  68 

minutus,  Palaeodelphis .  6 

miocaena,  Megaptera .  72 

Miosiren  kocki . . . 58,  67 

Mirounga . 98, 104,  105,  106,  108 

angustirostris . 99,  104 

Monachus  tropicalis . 77,  91 

moreni,  Cetotherium . 39,  40 

mortezelensis,  Eudelphis .  7 

mortezelensis,  Scaldicetus . 7, 16,  31 

mortselensis,  [ Scaldicetus ] .  7 

musculus,  Sibbaldus . 44,  46 

mysticetus,  Balaena . 42, 44 

Neobalaena  marginata . 44, 46 

nodosa,  Megaptera .  44 

obesus,  Hoplocetus .  8,9 

occidentalis,  Plesiocetus .  50 

Odobenidae . 99, 100, 101 

Odobenus,  12,  94,  95,  102,  103,  104,  105,  106, 

107, 108 

Odobenus  diver  gens . 99, 102 

Ontocetus . 1, 2, 12, 13,  30 

emmonsi . 11, 12,  33 

oxymycterus .  30 

Rostrum .  31 

Mandibles .  32 

Teeth .  33 


PAGE 


Orcopsis .  1,2 

oregonensis,  Desmatophoca . 71,  97 

Orycterocetus . 1,  2, 12,  13, 14,  20 

mediatlanticus . 11,  13,  31 

quadra  tidens . 10,  11 

Otaria  byronia .  75 

Otarid  (?),  new  genus  and  species .  93 

Tibia .  94 

Ribs .  95 

Otariidae . 71,  99,  100 

oxymycterus,  Ontocetus .  30 

pacifica,  Pliopedia .  97 

Palaeodelphis .  1,2 

Palaeodelphis . . . .  1,2 

Palaeodelphis  coronatus .  6 

Palaeodelphis  minutus .  6 

palmeri,  Parietobalaena .  54 

Paracetus . 1,2,  3 

Paracetus  mediatlanticus . 9,10 

Parietobalaena  palmeri .  54 

patagonicus,  Idiorophis . 6,  7,  9,  14,  30,  31 

patagonicus,  Physodon . 4,  5,  6 

Patriocetus .  37 

Phoca . 4,  78,  80 

fasciata . 79 

hispida .  78 

sibirica .  77 

vindobonensis . 77,  78 

vitulina . 77,  78,  79,  80 

Phocanella  pumila .  78 

Physeter,  4,  6,  10,  11,  12,  13,  15,  16,  17,  18,  19, 
20,  21,  22,  23,  24,  25,  26,  27,  28,  30,  31, 
32,  33 


Physeter  catodon . 11, 17,  25, 29 

Physeteridae . 1,3, 4 

Physeterula . 1, 2, 4, 13 

dubusii . 4, 14,  15 

Physetodon . 1,2 

physalus,  Balaenoptera .  44 

Physodon . 1,  2,  3,  5 

Physodon  leccense .  4 

Physodon  patagonicus . 4,  5,  6 

Physodontidae .  3 

Pithanotaria  starri . 74,  93 

Skull .  75 

Mandible .  75 

Cervical  vertebrae .  81 

Dorsal  vertebrae .  81 

Lumbar  vertebrae .  82 

Ribs .  82 

Sternebrae .  83 

Scapula . 77,  84 

Humerus . . . 77,  84 

Radius . 78,  86 

Ulna . 78,86 

Carpals . 79,  86 

Metacarpals . 80,  86 

Phalanges .  80 

Ilium .  83 

Femur .  83 

Patella .  84 

Tibia . 84,89 

Fibula . 84,89 

•  Tarsals .  89 

Metatarsals .  92 

Phalanges .  92 


Index 


119 


PAGE 

Platyrhynchus . . 1,2 

Plesiocetus . 36,51 

hupschii . 36,  51 

megalophysum . 51,  52,  53 

occidentalis .  50 

Skulls .  51 

Periotic .  55 

Pliopedia  pacifica .  97 

Pontolis .  98 

magnus . 97,  98 

Pontolis  cf.  magnus . 89,  98 

Astragalus .  104 

Calcaneum .  102 

Cuboid .  106 

Ectocuneiform .  110 

Entocuneiform .  107 

Mesocuneiform .  109 

Navicular. . .  105 

Sesamoid .  110 

Metatarsals .  Ill 

Pontoplanodidae .  3 

poucheti,  Diaphorocetus .  .  .  .2,  3,  6,  7,  9, 15, 22 

Priscophyseter .  1,2 

Prophoca  proxima . 77,  78 

Prophyseter .  1,2 

proxima,  Prophoca . 77,  78 

pumila,  Phocanella .  78 

quadratidens,  Orycterocetus . 10,  11 

rathkii,  Cetotherium . 36,  39, 41,  51,  54 


PAGE 

Rhachianectes  glaucus .  44 

ryani,  Balaenoptera .  71 

Rytiodus  capgrandi .  60 

Scaldicetus . 1, 2, 3,  5,  6,  7, 13,  31 

caretti . 7, 8, 16,  34 

grandis . 6,  7, 16 

mortezelensis . 7,  16,  31 

mortselensis .  7 

Scaptodon .  1,2 

schinzi,  Halitherium . 58,  67 

serresii,  Felsinotherium,  58,  61,  62,  63, 64, 66,  67 

Sibbaldus  musculus . 44, 46 

sibirica,  Phoca .  77 

Squalodon .  7 

starri,  Pithanotaria . 74,  93 

stelleri,  Hydrodamalis, . . .  .58,  61,  62,  64,  65,  67 

Thalassocetus . 1,  2, 11, 13 

antwerpiensis .  16 

Trichechus . 64,  65,  68 

latirostris . 64,  65,  67,  68, 69 

tropicalis,  Monachus . 77,91 

vandelli,  Cetotherium . 50,  51 

versabilis,  Megaptera .  72 

vindobonensis,  Phoca . 77,  78 

vitulina,  Phoca . 77,  78,  79,  80 

Xyne  grex .  38 

Zalophus . 75,  90,  95 

calif  ornianus .  99 


ABBREVIATIONS'  FOR  PLATES  1  to  6. 

The  same  abbreviations  are  used  on  plates  1  to  6  for  the  following  structures: 


Al.,  Alisphenoid. 

A.  inf.  anterior  infraorbital  foramen. 
Ant.  max.  anterior  maxillary  foramen. 
'Ant.  n.,  antorbital  notch. 

Ap.  max.,  apophysis  of  maxilla. 

Bo.,  basioccipital. 

Bs.,  basisphenoid. 

C.,  condyle. 

Eth.,  ethmoid. 

Ex.  oc.,  exoccipital. 

Fal.  pr.,  falcate  process  of  basioccipital. 
F.  hyp.,  hypoglossal  foramen. 

F.  m.,  foramen  magnum. 

F.  ov.,  foramen  ovale. 

Fr.,  frontal. 

H.  pr.  pt.,  hamular  process  of  pterygoid. 
Inf.  /.,  infraorbital  foramen. 

Inf.  max.  inferior  maxillary  foramen. 
J.  A.  C.,  jugulo-acoustic  canal. 

Ju.,  jugal. 

La.,  lachrymal. 

L.  cr.  max.,  lateral  crest  of  maxilla. 


Max.,  maxilla. 

Max.  /.,  maxillary  foramen. 

Max.  inc.,  maxillary  incisure. 

N.  A.,  nasal  passage. 

Na.,  nasal. 

Op.  c.,  optic  canal. 

Pa.,  parietal. 

Pal.,  palatine. 

P.  inf.  /.,  posterior  infraorbital  foramen. 
P.  max.  posterior  maxillary  foramen. 
Pmx.,  premaxilla. 

Pmx.  /.,  premaxillary  foramen. 

P.  oc.  pr.,  paroccipital  process. 

Prs.  presphenoid. 

Pt.,  pterygoid. 

S.  max.  superior  maxillary  foramen, 
S.  oc.,  supraoccipital. 

S.  or  pr.,  supraorbital  process  of  frontal. 
Sq.,  squamosal. 

Vo.,  vomer. 

Zyg.,  zygomatic  process  of  squamosal. 


120 


Fig.  1.  Dorsal  view  of  type  skull  of  Idiophyseter  merriami.  Cat.  Fig.  2. — Ventral  view  of  type  skull  of  Idiophyseter  merriarni. 

No.  24287,,  Mus.  Palaeontology. 

Restored  areas  appear  darker  than  original  surface.  By  oversight  fig.  2  is  made  smaller  than  fig.  1.  Both  should  have  had  same  reduction. 


KELLOGG 


PLATE  1 


KELLOGG 


PLATE  2 


Fig.  1. — -Lateral  view  of  skull  of  a  young  Physeter  catodon.  Cat.  No.  49488,  U.  S.  Nat.  Mus. 


Ma.v  :aux 

Max. 


Ex.oc 


a. 

Ap.  max. 

Pal. 


Max. 


S.  or.  pr. 


Fig.  2. — Lateral  view  of  skull  of  Idicphyseter  merriami. 
Restored  areas  appear  darker  than  original  surface. 


KELLOGG 


PLATE  3 


Tmx. 


I  ig.  1.  Lateral  view  of  a  skull  of  Kogia  hreviceps.  Cat.  No.  22015,  U.  S.  Nat.  Mus. 


Fig.  2. — Posterior  view  of  type  skull  of  Idiophyseter  merriami. 
Restored  areas  appear  darker  than  original  surface. 


Each  figure  about  one-eighth  natural  size. 


KELLOGG 


PLATE  4 


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KELLOGG 


PLATE  5 


Fig.  1. — Dorsal  view  of  type  skull  of  Orycterocetus  mediatlanticus 
(Cope).  Cat.  No.  9463,  U.  S.  Nat.  Mus. 


Fig.  2. — Lateral  view  of  type  skull  of  Orycterocetus  mediatlanticus  (Cope). 
Each  figure  about  one-eighth  natural  size. 


Fig.  1. — Dorsal  view  of  skull  of  a  young  Physeter  catodon.  Fig.  2. — Ventral  view  of  a  skull  of  a  young  Physeter  catodon. 

Cat.  No.  49488,  U.  S.  Nat.  Mus.  Left  pterygoid  and  palatine  removed  to  show 

relations  of  underlying  bones. 

Each  figure  about  one-eighth  natural  size. 


KELLOGG 


PLATE  6 


Fig.  1.  Dorsal  view  of  rostrum  and  mandibles  of  Ontocetus  Fig.  2. — Lateral  view  of  rostrum  and  dorsal  view  of  left 

oxymycterus.  Cat,  No.  10923,  U.  S.  Nat.  Mus.  mandible  of  Ontocetus  oxymycterus . 


KELLOGG 


PLATE  7 


liG.  1.  Ventral  view  of  mandibles  of  Ontocelus  oxymycterus.  Fig.  2. — Lateral  view  of  rostrum  and  dorsal  view  of  right 

(  at.  No.  10923,  U.  S.  Nat.  Mus.  mandible  of  Ontocetus  oxymycterus. 


KELLOGG 


PLATE  8 


KELLOGG 


PLATE  9 


Fig.  1. — Lateral  view  of  crown  of  a  mandibular  tooth  of  Ontocetus  oxymycterus  with 
outer  layer  of  cementum  removed  to  show  the  longitudinal  fluting  on  the  den¬ 
tinal  axis. 


Fig.  2. — Cross-section  of  a  mandibular  tooth  showing  internal  cone  of  ossified  pulp 
and  dentine,  and  thick  external  band  of  cementum. 


Fig.  3. — Endocranial  cast  of  type  skull  of  Metaxytherium 
jordani. 

Abbreviations:  F.,  frontal  lobe  of  cerebrum;  01.,  olfactory 
lobe;  S.  s.,  sagittal  sinus;  T.,  temporal  lobe  of 
cerebrum. 


KELLOGG 


PLATE  10 


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Figs.  1-3.  Anterior  views  of  dorsal  vertebrae  of  Metaxytherium  j or dani.  Fig.  1,  sixth  dor¬ 
sal;  Fig.  2,  seventh  dorsal;  Fig.  3,  eighth  dorsal. 

Figs.  4-6.  Lateral  views  of  dorsal  vertebrae  of  Metaxytherium  j  or  dani.  Fig.  4,  sixth  dorsal; 
Fig.  5,  seventh  dorsal;  Fig.  6,  eighth  dorsal. 

Figs.  7,  8. — Posterior  views  of  dorsal  vertebrae  of  Metaxytherium  jordani.  Fig.  7,  sixth 
dorsal;  Fig.  8,  seventh  dorsal. 

Fig.  9. — Posterior  view  of  fifth  metacarpal. 

Fig.  10. — Proximal  end  of  a  rib  from  left  side  of  body. 


M  U!;\M,Y 


KELLOGG 


PLATE  12 


Impression  of  the  type  skull  and  right  mandible  of  Pithanotaria  starri  Fig.  2. — Impression  of  the  bind  limbs  of  Pithanotaria  starri  in  a  slab  of 
in  a  slab  of  diatomaceous  earth.  Cat.  No.  11,  Museum,  Stanford  diatomaceous  earth.  Cat.  No.  26785  Museum  of  Palaeon- 

University.  tology,  University  of  California. 


KELLOGG 


PLATE  13 


